[englandmademe]

Hi

My broadband speed is running 50% of what is should. My macbook runs fine, so not a router/modem issue.
I've exhausted all software troubleshooting options, so now want to replace the airport card to see if this solves the problem.

I've pulled apart my machine previously to update the hard drive so I'm fairly comfortable opening them up, but I cannot find any resource online that points out where the airport card sits on my specific machine?

I've had a look at can not see it anywhere - it must be hidden under some kind of blanking panel...

Can anyone offer any help in the way of a link or advice? It would be much appreciated.

Thanks, Paul

[AKcrab]

It's under the right speaker.

[-Q-]

What year is it? This shows where the airport card is on the '09 model, but it's a bear to get to as you have to remove the glass:

[AKcrab]

He said it's white. That should narrow it down.

[indigoimac]

Before you go too crazy with this did you try completely reinstalling osx wiping the drive and all? I know you said you evaluated all the software possibilities, but just checking. Also, what do you mean by 50% slower -- out to the internet? lan file sharing? There are a hell of a lot of variables when it comes to network speed and I want to make sure we're rounding all the bases.

[englandmademe]

Thanks AKcrab - spot on, it was under the speaker. Bizarre place to put it and not particularly accessible, although at least didn't have to take the screen off.

Anyway I switched the airport cards (had another identical imac which got 'retired' due to severe graphic card issue) and it hasn't solved the problem... This appears to have ruled out a hardware issue.

I guess wiping the hard drive and doing a clean install of OS is a sensible thing to do but the thought of reinstalling all my apps and settings etc. doesn't fill me with joy. Although better than taking a hammer to my machine which is what I feel like doing at the moment.

To clarify the issue is that my 10mb wireless broadband is only around 4mb on the imac. But my powerbook happily gets 9.8 or similar. Even my kids eMac gets 9.5mb, so this is frustrating the hell out of me.

[AKcrab]

Instead of a complete reinstall, you could try nuking the following folder:
/Library/Preferences/SystemConfiguration

As soon as you trash it, restart your machine.

That will completely reset your network settings, more thoroughly than creating a new location.

[englandmademe]

Tried getting rid of SystemConfiguration - unfortunately did not work.

Looks like doing a totally fresh install is worth doing to see if it solves the problem. If it does then I guess I can live with having to reinstall all my apps.

[reader50]

Try moving the iMac to test in a different location. It may be close to metal sheeting or some cladding in the wall. Even a filing cabinet between it and the router. Check from across the room or in a different room to see if transfer speed recovers. You could also check which channel the iMac card is using - the other devices may be using a less crowded channel.

[P]

All devices on the same network use the same channel, but it might still help to change. If one neighbour close to the iMac uses the same channel as you use, then the iMac will have worse performance than the other devices on the network. Check your wireless neighbourhood and pick a channel noone else uses to see if that helps.

If you are in the UK, make sure that all devices are set to region UK. In the US, only channels 1-11 (802.11 b/g) are available, but in Europe we can use channels 12 and 13 as well. By setting your devices to the correct region, you enable the full range of channels. IME, very few people know about this, so channels 12 and 13 are often free.

Water pipes can also disturb WiFi performance and create standing waves, if you are unlucky. If that is the case, moving the iMac a few decimeters might help.

[englandmademe]

Thanks - I have the imac and macbook sitting next to each other on a desk so it seems unlikely that interference would be the issue.

How do I change the channel for the iMac? Do I have to access the router's admin screen to do this?

[P]

Yes. All clients are usually set to automatically scan all channels (inside the range that they're permitted to use by the region setting) and then pick whichever the router uses, so you have to change the channel on the router. Most default to 6 or 1, so try to avoid those channels.

[englandmademe]

Well I tediously went through all of the channels with unbelievable differences:

1 - 3.32mb
2 - 7.55mb
3 - 3.20mb
4 - 3.95mb
5 - 5.17mb
6 - 2.15mb
7 - speedtest.net was so slow I didn't wait for a reading
8 - 1.20mb (!)
9 - 5.95 mb
10 - 5.93mb
11 - 1.69mb

Obviously I have opted for channel 2 which seems to be the 'quickest' but it's still 25% slower than the advertised 10mb, and more to the point my macbook still happily gets 9.48mb regardless of channel!?

I couldn't see how to configure different channels for different devices on my Netgear WGR614 v6 although given the above I don't think that would help.

There MUST be something about this iMac which is causing the slow down. Will now resort to reinstall of clean system and report back!

[reader50]

I'm afraid P is correct. The channel is set at the router, and applies to all wireless devices on that LAN. I'd misremembered - you can't set the channel separately at each computer.

It sounds to me like your operating system is fine, reinstalling is probably a waste of time. My guess: the iMac has a poorer antenna than the later computers. You might test if it has directional sensitivity by turning the iMac to different angles, or moving it around the room. But it's probably not something you can fix.

If there is a simple path along a wall to the router, you could use a standard ethernet cable instead of the wireless connection. That would give you 100mb or 1000mb (depending on router) along with perfect reliability. Many people who have grown used to wireless seem to forget that wired connections always work perfectly.

[ghporter]

Originally Posted by englandmademe 

Well I tediously went through all of the channels with unbelievable differences:

1 - 3.32mb
2 - 7.55mb
3 - 3.20mb
4 - 3.95mb
5 - 5.17mb
6 - 2.15mb
7 - speedtest.net was so slow I didn't wait for a reading
8 - 1.20mb (!)
9 - 5.95 mb
10 - 5.93mb
11 - 1.69mb

Obviously I have opted for channel 2 which seems to be the 'quickest' but it's still 25% slower than the advertised 10mb, and more to the point my macbook still happily gets 9.48mb regardless of channel!?

I couldn't see how to configure different channels for different devices on my Netgear WGR614 v6 although given the above I don't think that would help.

There MUST be something about this iMac which is causing the slow down. Will now resort to reinstall of clean system and report back!

You've gone about finding the least busy channel the hard way, but at least you did it intelligently. Please keep in mind that there is significant overhead in any wireless network connection, so I think you're getting a GREAT connection with your MacBook.

The obvious question would be what is between your router and your iMac that is NOT between the router and the MacBook. It could be something like furniture, a water pipe, almost anything. That relatively minor difference between speeds for your iMac and MacBook is easily explained by any sort of interfering source or obstacle. One thing to try is raising your router higher above the floor. Bookcases and furniture can block a WiFi signal pretty thoroughly, so if your router is above the level of most furniture, you're likely to have better connections for everything.

[P]

Keep in mind that London is very busy when it comes to WiFi, so I'm not entirely surprised. From the looks of it, channel 7 has someone on it, and both 1 and 11 also have some takers. There is some overlap between the channels, which is why you see this continious range in speeds. The person in channel 1 is probably a bit away from you though, which is why channel 2 is working out.

7.5 is certainly not bad, though. It may be that the Macbook has a better antenna than the iMac, which is why it comes through better.

[englandmademe]

Thanks for the replies everyone.

I'm going to just live with 7.5mb on my iMac for the time being.

Virgin Media, my provider here in the UK do offer a 20 and 50mb service. I'm probably going to try and renegotiate up to 50mb soon, but I can't help but wonder what the deal would then be on my iMac...

If the 'best' I can get with my 10mb service is 7.5, would it follow that I will struggle to get above 37.5mb on the 50mb service (ie 3/4 of advertised rate) or does it not work like that?

There certainly is something to be said for keeping your main desktop computer as a wired device, unfortunately my router is in another room and it would be a major hassle to get wires to my iMac.

[ghporter]

Would you necessarily get only 37.5 with a 50Mb/s service? That all depends. If you mess around with the router's location and orientation (you don't seem to have mentioned just what router you have), you could find that the iMac gets a faster connection. Interference and signal blockage show up in lower speeds, which is why I think you just have something between the iMac and the router. But different routers have different antenna systems, which behave differently in relation to obstacles. It's worth a few minutes tweaking to see if you get closer to the speeds your MacBook sees, and this sort of tweaking is free...

[seanc]

In the case of the iMac being no-where near the router and you don't want to run an Ethernet cable, the other option is to eradicate wireless and use Ethernet over Power to connect your iMac to the router directly via the Ethernet port on your iMac and your buildings electricity supply. Homeplug II running at 85Mbps should do just fine.
Note: The location for the iMac and the router must be on the same ring main.

As for negotiating a faster speed, just hang on until they adjust the packages, which I think may be coming soon, then you'll probably get 20mb for the same price. We started out on 256Kbps 7 years ago and we're now on 10Mbps (and a new modem to be able to understand the upgraded QAM)

[P]

Also note the max capacity of the wireless standard you're using: 802.11g advertises 54Mbps theoretical speed, but that only comes to 19 Mbps throughput. If you're interested in 50 Mbps, better upgrade to 802.11n - go wired.

Ethernet over powerline was really tricky to get working, IME, but once it's set up it just goes and goes, and it FEELS way faster than 802.11g.

[seanc]

Originally Posted by P 

Ethernet over powerline was really tricky to get working, IME, but once it's set up it just goes and goes, and it FEELS way faster than 802.11g.

Really?

All of the kits I've used, you just plug one end into one socket, one into the other, the link lights come up and off you go!

[P]

I think I opted for the stupidly cheap no-name option. Plus the fact that the first kit I got was defect, so I had to replace it, although I figured that part out pretty quickly.

[englandmademe]

Thanks - yes I realise I will probably need to update my router to 'n' if I'm looking at 50mb broadband. Hopefully will get virgin media to give one to me! I will still need a good wireless connection for my iphone, macbook and possibly an ipad (he hopes!)

However for the iMac I'm really sold on the ethernet over power idea. It sounds brilliant. I'm really surprised it hasn't caught on more - seems to be one for the 'techies' only and not readily available or marketed here in the UK.

Will try to get a 200mb one sometime this week - I need to do a bit more research but will report back for those that might be interested....

[englandmademe]

Update to this thread....

I coughed up for a Devolo 200 AVeasy power over ethernet adapter.

Literally just plugged into router and into the imac and it worked! ZERO set-up!.

Now getting 9.85mb of my 10mb broadband! Definitely will be negotiating an upgrade to 20 or 50mb.

Really impressed with this device. Can see me forking out for another adapter and putting another mac upstairs.

[reader50]

If you want to measure the real speed the adapter can manage, don't use your internet connection. Instead, copy a 1 GB file over the LAN. Connect your MacBook to the router via ethernet so that the only stage being tested is the connection to the iMac.

(file size) divided by (seconds to transfer) = speed.

It's likely to be much higher than your internet service speed. Also, it will show you if a faster internet connection will be fully passed through the powerline adapter.

[englandmademe]

Thanks for the tip - will try that tomorrow! I guess this is pertinent if you wish to stream video from one machine to another...

[englandmademe]

I tested the file transfer speed this morning

I copied a 1.54 gb file from my macbook connected by ethernet to the router to the imac connected via ethernet from the powerpoint, and it took 3 mins 54 secs.

While not exactly slow, if this device is supposed to transfer at 200mbps doesn't that mean it should have taken 8 secs rather than 4 minutes!?

[ghporter]

Did you copy the file from within PowerPoint, or from the folder the file was in? PowerPoint saving files to new locations is often quite slow, and it does not save all at once.

[englandmademe]

No it was an .avi file sitting on the desktop of the macbook, copied onto the dropbox folder of the imac.

[P]

The 200 mbps on the powerline adapter is 200 megabits/second. The file is 1.54 gigabytes. Even with 100% efficiency, that's just over 1 minute, and there are many factors cutting that number further:

* The HomePlug AV standard, the most common version today, supports 189Mbit/s, which is "rounded" to 200 in marketing
* HomePlug AV supports half duplex, ie 189 Mbit/s in either direction, but not both at once. Appleshare doesn't work very well with this, as it wants updates on progress every so often. FTP might be a better test.
* 189 Mbit/s is at the physical layer, the bottom of the model. Every layer over it adds overhead to some extent.

You could try an FTP transfer to see if you get better numbers, but it's not going to be close to 1 minute, and certainly not a few seconds.

[englandmademe]

Thanks, I might try ftp when I get a chance. I thought 200mbps meant megabytes rather than bits. Under 4 mins for 1.5 gig is still good.

[reader50]

You got 50+ megabits per second on that transfer. An internet upgrade to 20 mbs or 50 mbs will reach the iMac.

Since your Netgear WGR614 has ethernet 10/100 ports, 100 mbs is your upper LAN limit.

[englandmademe]

Thanks reader50 - good to know. To be honest I'd given up trying to work it out - too many zeros!!