Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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...

share|improve this question

A few tips:

  1. Don't leave iStumbler or other network scanning tools running on the same machine that's having trouble joining the network. Scanners force the client to repeatedly tune to other channels to look for other networks, which can get in the way of that client's ability to do the right thing on the channel it's supposed to be on for the current network it's trying to join.

  2. Try running the airport -s command in Terminal to see a detailed listing of networks in range, that includes some info that iStumbler leaves out:

    alias airport='/System/Library/PrivateFrameworks/Apple80211.framework/Resources/airport'
    airport -s

    Pay special attention to the "CC" (Country Code) column. Are all networks in range reporting the code for the country you're in (if they report one at all)? If any are reporting the wrong country, it can cause some clients to get confused at boot/wake time. For example, if you're in the UK which like the other EU (ETSI) countries allows channels 1-13, and a nearby, misconfigured AP says "US" which only allows channels 1-11, then clients that see the US AP first may have trouble joining other APs that happen to be on channels 12 and 13.

  3. In the case of networks seemingly refusing a correct password, try deleting any saved passwords for those networks from your keychain. Use the Keychain Access utility (in /Applications/Utilities/) to do that. You might also want to delete those networks' entries from System Preferences > Network > AirPort > Advanced > AirPort > Preferred Networks. Then re-join the network and let the system re-create clean versions of those entries.

share|improve this answer
Very good answer, neighbour on ch 1 is set to US. Swapping to 11 seems to have improved life (not sure why the iPhone and iPads seem more immune - I'd have thought same protocol stacks from Apple). I'll see if I can get neighbour to set UK for a freer future! – cwinte Jun 30 '11 at 6:37
A thought: if the MBP goes to sleep connected on ch 13 why not look at that first when it wakes up and carry on happily if it can? – cwinte Jun 30 '11 at 6:45

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .