This is my son's MBP 7,1 running Snow Leopard 10.6.7. Router signal is fine since iPad, Wintel on same table 20 feet from router are fine. the MBP however frequently wakes and fails to find the internet. iStumbler can see 1 neighbours hub and my garden hub are there but can't get to the normal DIR655 wifi... no ping no en0 or en1 device seems to exist. Airport off and on does not help. He just resets router and it all works but this does not please me! I must admit the winter sometimes seems to loose connect too, but less so. The DIR655 (hardware rev A3) is on the original EU firmware 1.10, I'm cautious about jumping to latest 1.31EU since no downgrade seems to be possible and that feels a bit risky as so much is set up and working fine. If I use the DIR655 admin web and release the lease the MBP has then wake it all worked OK. So I suspect lease timing/locking issue but unsure how to check up, plus why iStumbler seems to say the network is not visible at all when I sit on the iPad right next to it just fine.. I do not think there are any channel overlaps and we also have RFquiet DECT phones (Orchid) that are silent until lifted or called. Anyway signals all show low interference and high throughput except for this failure to connect.

Just walked the MBP to the garden office and iStumbler now sees the more distant DIR655 signal although it will not connect to it (does not show under Sys Prefs > Net>Network names) even after airport off & on... It also refuses to connect to my garden network (an old Belkin acting as AP wired to DIR655), the signal it can see and even net name in Sys Prefs > Net>Network names (2 mins later):NOW both names ARE visible, but both fail to accept the correct WPA2 password and keep asking again after failing to connect.

IT ALL MAKES NO SENSE TO ME. Just revoked the lease for the MBP on DIR655 and no changes although this seemed to help MBP wake into connection 1 hour ago. OK a bit of walking about to report. Carried MBP across garden towards DIR655, a few other wifis show up on iStumbler, low signals all channel 1. Right next to DIR655 but iStumbler not showing it, although most other wifi's have gone. I'd say iStubler is suffering timeouts&hangs but hard to be sure. Lots of attempts to Airport on/off, join other etc and suddenly I get to connect, get given new IP (I revoked), can browse. Walk away, connection drops quite soon at 30 feet then reconnected briefly then died again. MUST ATTEND ELSEWHERE FOR A BIT...