I have two IBM/Lenovo Thinkpads, both running Gentoo Linux.
One is a T40 with an Intel 2915 ABG wireless adapter, and the other is a T500 with an Intel 5100 AGN.
When both systems are running and connected to my WPA2 wireless network, either one or the other will have a working network connection, but never both. The wireless driver will indicate that the connection is active, but I won't be able to ping the router's internal interface and domain lookups will fail. I have tried all manner of resets. The only thing that gets networking working again is to turn one of the Thinkpads off.
The wireless router -- a Sphairon IAD 3232 provided by my Internet provider -- seems to be able to handle multiple connections from other devices just fine. This problem only appears when both Thinkpads are on the network. The Sphairon supports 802.11 N, and the T500 is the first device that I have which supports this. I wonder if that is a possible factor in this problem. (My roommate has a MacBook, but I don't know if it has an N adapter in it. He has yet to notice any problems.)
It turns out that at least one other person has had similar issues:
He claims to have "solved" it by switching to WEP encryption, which is not an acceptable solution.
What might be causing this, and how can I go about troubleshooting and resolving it?