[Keda]

I move my iMac between two locations. The first is downstairs, where I leave it during the week, and the second is upstairs, on weekends. I am doing this because I have recently started a business, and use the iMac in my home office. My airport base station is downstairs, but signal is very good throughout the house.

Anyhow, when the Machine is upstairs, it intermittently drops the airport signal. More strangely, the iMac can not find the base station after the signal has been dropped. Sometimes, the base station will appear after a while, but I usually need to logout or restart. I have been observing this problem for a couple of weeks, but am not able to make any sense out of it.

So, where do I start? I have not noticed any patterns, besides occurring upstairs, and am stumped. Any ideas?

iMac CD 20"
2GB RAM
256 x1600
10.4.8
AirPort Extreme, channel 6, 802.11b/g compatible

[kick52]

you might have interference.. have you checked the aerial of the base station (i dont even know if there is one..)

[Keda]

I don't think there is any aerial to adjust...at least not externally.

The weird part is that the iMac will not even see the base station after a drop, but a 12"PowerBook that is right next to it has full signal. Seem like a problem on the iMac.

[Tsilou B.]

I have seen the same problems with my iMac. I wasn't able to solve it, so I bought another WLAN router (I'm using AVM Fritz!Box routers, not original Apple base stations), installed it upstairs (my other router is downstairs, too) and connected the two routers with WDS. Now my iMac uses the second router and works just fine.

BTW, my Toshiba notebook also worked fine upstairs before I bought the second router.

[CharlesS]

See if someone nearby is using one of those cordless landphones that operates on the 2.4 GHz band. If they are, it could cause your signal to drop whenever they make a phone call, especially if the phone is a Panasonic (why that brand is so popular is beyond me).

[JKT]

Download iStumbler to monitor the signal from your Airport Station to see if it is as strong as you think it is or whether it is dropping.

The other thing to try is changing the channel you are broadcasting on.

[Rosieo]

I am experiencing this also on my brand new iMac. It sits about 2 feet from the router and I am constantly getting a dropped signal. My son just bought himself a MacBook Pro today and is experiencing the same thing. We even unplugged our cordless landline completely, thinking that was the problem but it is still happening. My husbands wireless Dell is not experiencing this. Any ideas as to what is happening. I even called Apple and they were not able to help me.

[steve626]

The suggestion to get iStumbler is a good one. You and some of the other users could be seeing interference from (a) other routers from neighbors, (b) microwave ovens (yours or neighbors'), or (c) telephones (yours or neighbors'). The iStumbler program would indicate something about (a). Once your airport card latches onto one of these "wrong" signals, it may stay latched on and only a reboot might cure the problem, and then temporarily. In my house, I can see two routers from neighbors, their signals are very strong (luckily not strong enough to cause me trouble), and my house is a healthy distance from those houses. In condos it can be much worse because the units are closer.

By the way, sometimes, when someone turns on our microwave (it's not every time, but I've noticed the correlation), my G4 laptop immediately drops the signal from my wireless Belkin router, yet my daughter's iMac G5, which is twice as far away from that wireless router, stays fine. A microwave from a neighbor could also wreak havoc. When I have that microwave interference, sometimes the G4 laptop grabs the signal back immediately, or sometimes I have to reboot.

If changing the channel and moving the location of your router or changing its antenna orientation doesn't fix things, you may have to investigate something other than the wireless setup you use to distribute your internet signal. Another possibility is to buy one of those newer routers with multiple antennas that emit a much stronger signal since each antenna is somewhat directional.

Also -- two computers side by side might be impacted by this issue quite differently because the internal antenna location and orientation for picking up the wireless signal could be different. However if two identical Macs side by side show different sensitivity, then it could be one of their internal airport cards that is contributing to the problem.

[Keda]

Ok, I DL'd iStumbler, and had it running when my Airport dropped out. What should I be looking for?

[steve626]

Originally Posted by Keda 

Ok, I DL'd iStumbler, and had it running when my Airport dropped out. What should I be looking for?

iStumbler might be useful in seeing if other airport networks or wireless routers are interfering with your wireless network. iStumbler should show your router (by name and make) and others (name and make) with a detectable signal.

For instance right now I can see my own router (a Belkin) with a signal strength of 30 and "noise" at level 9 (which is fairly weak, corresponds to only about 2 out of 4 possible bars in the airport menu display -- my laptop and me are pretty far from my own router but it works pretty well nonetheless), and one neighbor's router (also a Belkin) shows up with a strength of 17. another neighbor's router (this one is a Linksys) shows up with signal strength of 15. You can see the names of the routers and the models in the iStumbler display.

For comparison, when I move closer to my router I get a signal strength of 70 (4 bars out of 4 possible) and noise level of 6.

iStumbler also tells you what channel the routers are using. This can be useful if you see routers of the same make as yours broadcasting on the same channel as yours -- that's a good indication that you might want to consider changing the channel on your router to move to a different frequency than the other guys.

If the number and strength of the other routers versus yours seems pretty much constant, and if your router's signal is stronger than the others and you aren't using the same channels, then it might be that other types of interference are at work (2.4 GHz portable phones, microwave ovens for instance). I don't know, for instance, if iStumbler would reveal anything when someone turns on a microwave oven and "jams" you ... maybe your airport signal strength would show a decrease at that moment, however. iStumbler shows a little graph displaying wireless signal strength versus time and it updates it every second or two, so a dip in strength would be clearly seen.

If your computer is portable, you could take it to a Starbucks or hotel or university or some place where you know there is good wireless signal, and see how your computer performs. If the dropouts are gone, then you can at least rule out a bad airport card or software issue in your computer. I'd then focus on your airport base station or router setup, or those above mentioned potential sources of interference. Can you get a friend to bring a laptop to your place to see if he has the problem you have experienced?

[Keda]

Thanks for the explanation.

Unfortunately, I think there is more to the problem than interference. About an hour ago, I brought my computer upstairs. The signal dropped just a few minutes ago. I tried turning AirPOrt on/off, but it could never acquire the base station. I also tried turning AirPort on/off in the Network prefs. My hope was that the card would reset. After a few minutes, I gave up and restarted....which brings me here.

This pattern is consistent. The signal will drop, not reconnect, but reconnect after a restart, with the menu icon reporting full signal. If the problem was only interference, then why would the signal reappear?

I think that something software related needs tweaking. Is there a process that will cause airport to restart?

[steve626]

Unfortunately, I am not very familiar with the Airport Base Station devices because at home I use a Belkin router and at work various non-Apple routers are deployed. Maybe someone else can help you with the Airport Base station possibilities. I would consider at least checking for firmware updates, software updates, and "reseting" the base station if that is an option.

As you know, both the hardware and software that resides in your computer and in your Airport Base Station must be working right for the wireless network to work. I would for now try to devise experiments to see if the problem is in your computer or in your Base Station. For instance, take your computer to another wireless access point to see if the problem reappears ... if it does then that points to your computer, at which point you can start to decide if it's hardware or software related. Or ... bring another computer that is known to work right wirelessly to your house to see if it drops the connection also. If it does, then start to focus on your Base Station (hardware and/or software), or maybe think some more about interference in your local area. Interference is tricky because it can be happening even though you show a "full signal strength" -- the signal might just happen to be one that a computer cannot talk to (microwave, phones, etc.).

[NordicMan]

Originally Posted by Tsilou B. 

I have seen the same problems with my iMac. I wasn't able to solve it, so I bought another WLAN router (I'm using AVM Fritz!Box routers, not original Apple base stations), installed it upstairs (my other router is downstairs, too) and connected the two routers with WDS. Now my iMac uses the second router and works just fine.

BTW, my Toshiba notebook also worked fine upstairs before I bought the second router.

Have you used an Apple Airport? Did you find that you preferred the German(Austrian) router?

[Keda]

I really wish this had not been moved to 'Networking.' I am convinced that this is an issue with the local machine, which can be resolved be resetting that internal AirPort card (if possible). Why?

- Full wireless is restored instantly after a reboot
- All other Macs (1 G4 PowerMac, 2 12" PBs, & an Intel 20 iMac) maintain signal from any location
- If iMac sits for a long time (i.e. overnight) the airport re acquires the signal

I there any way to test the health of my AirPort car that came with this iMac? Can it be reset, without having to reboot (real PITA)?

[ghporter]

If it has to do with the AirPort card at all, it's a networking issue, NOT an iMac issue.

You can start by going to the AirPort icon at the top of your screen, control-clicking on it, and selecting "Turn AirPort Off." Wait a minute or two and then turn it back on the same way. That almost always fixes the "won't connect after sleep" problem, and will most likely fix yours as well.

Now for why you might lose signal strength due to interference. A microwave oven operates at almost exactly the same frequency band as WiFi (and AirPort is just Apple's trade name for WiFi hardware). Older microwaves are often leaky, and that 2.4GHz RF signal, if it's in just the wrong place, can cause havoc with WiFi networks-BUT ONLY WHILE THE MICROWAVE OVEN IS RUNNING. 2.4GHz phones can also do the same thing, and again, only when in use. It's quite possible that when you move your computer you're putting an interference source between it and your base station. When the interference starts, the AirPort card loses the network and can't find it again because when it starts looking it "searches" by choosing slightly different frequencies, anticipating that the network glitched and skipped the frequency it was on (WiFi networks use a form of "frequency hopping" called Direct Sequence Spread Spectrum, which means that they step from one discrete frequency to another in a set pattern). This is basically the same thing that happens when a computer doesn't connect when it wakes up-the card doesn't know it was asleep and the network's moved on from the last frequency the card knew about.

[Keda]

The thing is, none of the other Macs (1 PB is next to the iMac, the other is 1 room away) drop their signals, but it is happening repeatedly on the iMac. As a matter of fact, I just had to reboot to get on the network.

I have turned on/off the AirPort card, but this does nothing. Logging out seems to have corrected the issue once or twice, but not consistently. The only reliable means of regaining my connection is to reboot. Needless to say, this is not convenient in the least.

Is there anyway to reset the Airport card w/o rebooting? Does the on/off method actually shut off power to the card?

[ghporter]

Some AirPort cards do, others don't. I think I'd be rich if I figured out what particular factor causes it and how to specifically correct it.

Turning off the AirPort card shuts off the radio system (it's safe for airline flights) and it also tells the card that when it turns back on it's time to look for a network. Your problem is very odd in that a reboot is required to get the card working again-it looks like there's more than the card involved.

Do you have the latest and greatest firmware loaded on your card? It might be an item to check here-and maybe forcing a reload of the latest if that's what you have would be a good idea. No, I don't know how to do that...sorry.

[Keda]

Man, this is getting really aggravating. I'm bumping this thread in the hopes that THE Airport guru might stumble across it.

I've had to reboot twice, because the AP signal has dropped. Shutting down works (as usual), but turning the card off doesn't seem to have any effect...even when I leave it of for a loooong time.

AirPort firmware is version 4.80.46.0. I don't think I'm going to mess with this yet.

Heeeeeeeeeeeelp!

[Keda]

One other question....

I there is a hardware problem w/the AP card, might it exhibit itself this way?

[Keda]

And another...

I set my base station's channel to 'Automatic' and it is now using channel 1. Is any channel particularly better than another?

[Keda]

I see this as two separate problems: 1) signal dropping 2) iMac needing to restart to reacquire. I have found a 'solution' to problem #1...which ultimately prevents problem #2 for happening.

I moved my airport express from my printer to a location near my iMac, and set it up as a WDS. Since then (day and a half) there have been no drops on the iMac. Of course, I now need to buy another Airport Express to make my old setup work.

While this is a workable solution, it does not make me feel satisfied. I was never able to find out what is going on w/my AP card in the iMac. Also, none of the other Macs in my house are experiencing this problem. SO, its a bit unsettling. Not to mention that I'll need to buy another APX. But, atleast Im not dropping the signal anymore.

[ghporter]

I think an explanation of where everything in your network is physically would help. I'm particularly curious about such things as wireless/cordless phones and microwave ovens that might be between your base station and your iMac (on a direct line, not in the walking path between them). And it would be good to know what kind of structure you're in-both the kind of residence (apartment/house/townhouse) and the kind of construction materials involved. Some masonry walls are horrible to try to get a signal through, but if your wood-frame walls are filled with pipes and conduits that could be a major problem too.

Finally, have you reseated your AirPort card and its antenna connection? I'd go for that before looking at any other hardware issue.

[Keda]

Sure...here's a quick-n-dirty floorplan.



The single-family home was built in 1934. Walls are drywall. We have a microwave oven, which sees lite use. No land lines in the house.I have vonage downstairs in the office. The PowerBook locations obviously change...but these are common spots. The main airport is in the basement.

As I mentioned, none of the other machines have this problem. But, this is the only Intel Mac. Could this be a reason? Different chipset, etc?

Lastly, how do I reseat the card? My iMac came pre-configured w/AP.

[robxlvideo]

Sorry Double post please read below (If you suffer from insomnia!)

[robxlvideo]

Hi there
Just found this thread on Google. I have been having exactely the same problem now for about two years with an Ibook G3. The machine see's and connects to the wireless network and after about an hour of use the connection will start to drop and reconect. Sometimes the cycle is only a few seconds and on other occasions it can take several minutes for it to return.
Usually the laptop will not see any wireless network the moment it drops.
I believe that the problem is only with the Laptop and it's airport card.
I have used the laptop on at least 7 different wireless networks over the last two years, I myself have moved three times (Twice too many!) in the last two year. I am now on my third wireless router at home. Four other computers (2 mac's, 2 PC's) with wirless cards are currently using the same connection and have no problem.
Whatever circumstances changes the one constant is that the Ibook airport will drop and reconnect.

If the Airport Guru is out there please help. I am prepared to offer up sacrifice to get this fixed!!! How about a Dell pc burnt to dust????

Thanks Folks

Happy New Year

Rob

[IceCaves]

I have the exact problem, a single airport client intel iMac that looses signal when all others do not and only a restart will allow airport to recognize the signal again...

In Apple's discussion boards one poster says the solution is to go to sys prefs > Network > Show Airport > Preferred Networks and then delete all prefered network listings and add current live signals and that solves the problem.

I am trying it now - we'll see.

-Jeff

[ghporter]

I've seen that solution used for a couple of "signal dropping" problems, and it seems to work pretty well. Please let us know how it works for you, as the iMac seems to be having the most problems with this lately.

[acorder]

I realize this thread has started to become a bit dated, as well as superceded by a thread in the Networking forum, but I thought I'd comment on someone's suggestion of using iStumbler to note any other competing wireless signals. When things were working well network-wise for me (on my 20" iMac CD), I was seeing signal strength of between 35-40 and noise of 8-12 or thereabouts. However, in recent weeks as this network-dropping issue has forced itself on me, iStumbler reports signal strength of, and I kid you not, 65450-65468 and noise of 65440-65442. Now, I'm no networking or mathematical genius, but those don't seem like reasonable scaled numbers to me. It does not, however, seem to have any direct effect on my connection, as right now my linksys router shows signal strength of 65465 and noise of 65440, and I have two (occasionally three) bars in the Airport signal strength indicator in the menu bar. Just thought I'd throw that out there in case anyone might know why the numbers are freakishly huge. I'll go dink around the Networking forum now to see if there are any related posts...

[TristanM-Tx]

I have an Airport card that has done this before occassionally when I was on our local college campus (AP's everywhere), but only once or twice, and when I first got it-- not as often as it has lately....
My card will simply die on me until I restart. No networks show up at all- even though I am surrounded by several APs. Kismac reports in the console logs on firing it up (prior to resorting to restart) that the individual channels are not being listened to by the card, as if the card is ignoring all input-output, or that a daemon it requires has gotten killed. I have restarted several times in the last 24 hours to get it to work again. Interestingly, it did come up this morning after being in sleep mode all night.

It would be nice if the folks on the phones at Apple were educated enough or would be more reliable so I wouldn't have to nearly scream at them to pass me to a teir 2 rep =/ I always end up wasting 5 minutes with a teir 1 support tech who is clueless about anything I end up needing to inquire about.
(I have alot of stories but I will spare posting them

[dunerunner]

I to was having this problem and the fix for me was as simple as going to System Preferences...Network... then under the Airport setting changed the "By default, join:" from automatic to preferred networks. Has not dropped in 48 hours.

Hope this helps.

Originally Posted by Keda 

I move my iMac between two locations. The first is downstairs, where I leave it during the week, and the second is upstairs, on weekends. I am doing this because I have recently started a business, and use the iMac in my home office. My airport base station is downstairs, but signal is very good throughout the house.

Anyhow, when the Machine is upstairs, it intermittently drops the airport signal. More strangely, the iMac can not find the base station after the signal has been dropped. Sometimes, the base station will appear after a while, but I usually need to logout or restart. I have been observing this problem for a couple of weeks, but am not able to make any sense out of it.

So, where do I start? I have not noticed any patterns, besides occurring upstairs, and am stumped. Any ideas?

iMac CD 20"
2GB RAM
256 x1600
10.4.8
AirPort Extreme, channel 6, 802.11b/g compatible

[siflippant]

Originally Posted by dunerunner 

I to was having this problem and the fix for me was as simple as going to System Preferences...Network... then under the Airport setting changed the "By default, join:" from automatic to preferred networks. Has not dropped in 48 hours.

Hope this helps.

Hey! I just posted similar in the Macbook forum... I tried this a few days ago and hopefully it will be a permanent fix - I haven't had any further drops in airport [and the need for a restart] since last week... *touch wood*

So for anyone else searching for a possible solution I recommend trying the same "By default, join:" setting...

Hope it works bro!

[MarkF]

Keda,
I wish I would have stumbled onto this post in November --I would have backed you up. I have the exact same issue and I positive that it is not interference related. One of two things happens:

1. Signal looks fine but can not connect. Reboot corrects problem.
2. Signal is gone. Reboot and signal is fine again.

I am going to try the "preferred networks" thing now but I am skeptical.

Mark

[frdmfghtr]

Surfing wirelessly today, after some time of inactivity the AirPort disconnected and wouldn't reconnect, even after cycling it on and off. A full reboot fixed the problem.

Searching for info on this (STILL! Why do we put up with random AirPort dropouts?? If I get a few more I'm taking my new MacBook back for an exchange), I came across this little tidbit at MacBook - Appledefects

* Many users report inexplicable dropping of wireless connections on 802.11b/g networks.

The airport shuts off after a period of inactivity when on battery power. My solution is to open a terminal and type:
nohup ping -i 10 google.com > /dev/null &
This will prevent the airport from sleeping until your next reboot.

[siflippant]

Originally Posted by frdmfghtr 

Surfing wirelessly today, after some time of inactivity the AirPort disconnected and wouldn't reconnect, even after cycling it on and off. A full reboot fixed the problem.

Update. The airport is still dropping despite using the option to connect to a preferred network. One tip, suggested by Simon in another thread was to sleep instead of reboot. This DOES work and is obviously faster than a restart.

Last night I had to put my MBP to sleep 6-7 times [or more] to enable continuous surfing. I REALLY do hope Apple can come out with a fix pretty soon...

[Cadaver]

I was having a similar problem. MacBook Pro (2.13GHz Core Duo) was losing network connectivity, even inches from the AirPort Extreme (802.11g) base station.

I can see 7 of my neighbors' wireless networks, too (surprising, since my neighbors homes are between 0.5 to 2 acres away). Using iStumbler, I could see they were mostly on channel 1 or 11. My network was also using channel 1. I have 3 AirPort Express units as well, one for each of my two TiVos and one for my XBox 360/stereo (AirTunes), connected via WDS.

I reset the AirPort Extreme base station to channel 6, and reset all of the AirPort Express units via the AirPort Admin app's automatic WDS configure tool, setting "allow wireless clients" on the Express units to "On."

My MacBook Pro no longer drops the WiFi connectivity. Yippy!