[Eug]

Is this a common behaviour? Sometimes with my iPad 2, when I leave it for a while and then come back to it, it retains the WiFi connection but doesn't seem to be able to connect right away to it. If I wait long enough (eg. 1 minute) it often works fine, or if I turn it off and on again it will work fine.

I am NOT using an Apple Airport. I am using some TrendNET TEW-432BRP 802.11g units. I have a bunch in the house, and they all work fine with my iPhone 4, my Intel Macs (C2D and i7), and my G4 Macs. The only problem machine is the iPad, and this behaviour is intermittent.

Is this a problem seen with other WiFi access points/routers and the iPad (2)?

Note, the actual routing is done by an Alcatel VDSL2+ modem/router. The WiFi access points just act as dumb WiFi to Ethernet bridges/APs, with WPA security. DHCP is done by the modem/router. (I'm not using WPA2 because some of the units do not support WPA2, but I did try WPA2 with one of the access points and got the same behaviour.)

[Eug]

Apple just says use WPA or WPA2, not WEP.

iPad: Issues connecting to Wi-Fi networks

Some Wi-Fi routers using WEP wireless security may cause intermittent disconnects to iPad which requires re-typing a password. Using WPA or WPA2 wireless security on your network will correct this issue.

It also says to adjust screen brightness. WTF?

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However, this guy says he's having problems with WPA2 AES, and gets it to work using WEP.

iPad can’t connect to my AES WPA2 Wifi � CornerEdge Blog

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This guy didn't test WPA, but did test WPA2 and WEP. WEP caused problems, but WPA2 worked fine.

How to Minimize Wi-Fi Problems With the iPad: Mobile Technology News �

So, I'll give WPA2 a shot again, but that means removing one of the access points. All my units are TrendNET TEW-432BRP units, but one of them doesn't support WPA2. All of the remaining ones are now set for WPA2 with Auto TKIP vs AES.

I'd consider buying the Airport, but they cost too much and people have reported problems with that too.

[Eug]

Still doesn't work 100% of the time. I have no problems with my iMac, iBook, my MacBook Pro, or my iPhone 4, just this @#*!)$(^;{)!# iPad 2.

[Cold Warrior]

You could try dhcp with MAC address reservation. Maybe it's an issue in dhcp with leases and renewals.

[Eug]

Hmmm… Thanks, could be. I do have a number of TrendNET access points spread around the property, but if I understand it correctly that wouldn't matter. I'd just have to reserve that MAC and IP address in the router, so just a one-time setting and that's it. Or alternatively, I could assign a fixed IP address to the iPad in its WiFi settings, no?

However, in the interim I took a different (almost) brute force method to bypass the TrendNETs altogether. I have two additional Airport Express units I had been using in Ethernet-only mode for iTunes streaming. I have since activated the WiFi on those too, with a separate SSID specifically for the iPad (and guests I suppose), and being Apple products they seem to behave more nicely with the iPad.

If I were to try turning off the Airport WiFi again and using the TrendNETs, would manually setting the IP address in the iPad's settings do roughly the same thing you're suggesting? I have set the router to dish out addresses via DHCP in the 50-200 range, but have manually set other things to IP address outside that range. eg. My printer is 20, just so I always know where the printer is.

[Cold Warrior]

By turning off the express bridge mode, it's created a 'double NAT' and another subnet on your LAN. If it works, that's ok but not idea (subnets within subnets can break file sharing or network printing when hosts and devices are across subnets).

I don't know for sure if a reservation would help, but it's a thought. With your airport expresses, it may be that apple's products are better, or in some way work better with iPad. I don't have any way to validate that.

[Eug]

The Airport Express units are still in bridge mode in the above setup. No double NAT. The only difference is that I had a different wireless SSID with the AE units than I did with the Trendnet units.

Before it was Ethernet --> AE --> iTunes streaming (WiFi off completely)
Now it is Ethernet --> AE --> iTunes streaming and WiFi

However I got the iPad to play nice with the other Trendnet access points simply by giving the iPad a fixed IP address. No more pausing issues. It does seem you may have been right about the DHCP issue. I'm just confused as to why it occurs with the iPad if the iPhone 4 doesn't have the problem.

[Nivag]

I've switched to static IP about an hour ago and it's not stalled once or cause TuneIn to buffer either. Brilliant!
The router is an O2 supplied one.

[Eug]

The problem began recurring again, even with a fixed IP address. Granted, it was much less common than before, but still occurred once in a while. Moreover, I started noticing it a bit with my iPhone 4 over WiFi too. Very, very irritating.

Well, there is another solution, at least in my case. The answer was to reduce the Beacon Interval for my wireless access points to 50 ms, from the default to 100 ms. That adds potential overhead to the wireless transmissions, but in real life it has actually increased my throughput rates, and more importantly, the iPad 2 now no longer loses the connection. Also, I no longer need to use a fixed IP address. DHCP works fine now.

This fix has been reported in a number of forums, as well as in this DD-WRT video. (I'm not running DD-WRT at the moment though, FYI.)

iPhone 4 and iPad 2 router disconnect fix - DD-WRT settings - YouTube