Wifi Stalling at Work

November 13, 2012 3:55 AM

At work, my wifi connection frequently stalls (MacBook Pro 9,1, OS X 10.8.2). The connection never drops, but websites will "hang" while loading and I am unable to receive/send mail. Although I'm still connected, if I click the Wifi icon on the menu bar so that it starts "Looking for Networks", the connection is immediately restored. This happens every 4-5 minutes.

This also disrupts any file downloads that take longer than a few minutes, causing them to stall (but not stop... the Chrome download manager still shows them as downloading, but the progress freezes and the speed slowly drops.)

Occasionally the connection isn't restored by letting it "Look for Networks". In this case, if I turn Wi-Fi off and then immediately back on again, it connects without a problem and works fine, until it stalls again several minutes later.

This never happens with my home wifi connection, so I don't think it's my wireless card. Other computers (and my iPhone 4) connect fine to the work connection at the same location, so I don't think it's the router at fault. I don't have any firewalls/VPN/etc. running. My only guess is somehow my laptop is configured incorrectly. Is there a way I can better diagnose this problem (perhaps by monitoring the traffic?) Has anyone run into a similar problem before? I'm in Germany, if that matters at all.

posted by Yiggs to computers & internet (10 answers total)

Has anyone run into a similar problem before?

I have the identical problem (at home, irritatingly) and have not solved it; in my case it is only intermittent, so ignoring it has been possible. So you aren't crazy, and if someone does have a solution, I'm all ears.
posted by Forktine at 6:32 AM on November 13, 2012

Have you tried changing the default MTU setting?
posted by 8dot3 at 6:34 AM on November 13, 2012

I have the same (but less frequent) problem.
posted by nile_red at 7:10 AM on November 13, 2012

Some have had luck with deleting some of the preference files related to Airport and Networking. In case something has become corrupt, deleting these might fix the problem. They will be recreated automatically when you start your computer.

com.apple.airport.preferences.plist
com.apple.network.identification.plist
NetworkInterfaces.plist
preferences.plist

These are located in Library/Preferences/SystemConfiguration.

Source: http://www.switchingtomac.com/tutorials/osx/macbook-pro-constantly-dropping-wireless-connection/

This worked for me at work....
posted by rryan at 8:09 AM on November 13, 2012

I've been working on it some more, and while it's not entirely fixed, it is significantly better now.

I followed some advice from this (massive) thread over at discussions.apple.com, suggesting it may be an issue with the DNS. I went to Network Settings > Advanced > DNS and removed the three DNS servers that were (automatically?) in the list. I then added Google's free DNS server (8.8.8.8) as the only DNS server, applied the settings and rebooted my wifi connection. This seemed to be an immediate improvement. However, about 45 minutes later, it stalled again as described above.

I then tried manually resetting the MTU. I followed the directions here to manually determine my network's MTU, which I was able to determine was the standard (1500). Although it was already automatically set to 1500 under Network Settings > Advanced > Hardware, I set it manually to 1500, applied the settings and rebooted the connection. I didn't notice any difference, but it did stall again about 30 minutes later. Following 8dot3's link, the author mentions that 1453 bytes is "just small enough to maintain a consistent connection with most networks but just large enough to not cause any slowdowns." I changed it to 1453 about an hour ago, and so far it has stalled once, so I'm not sure if it actually made a difference or not. According to speedtest.net my speed has not been significantly changed.

One interesting thing: when it last stalled, I pinged google.com and was able to ping it just fine, even when my browser had stalled. After about 12 pings, the browser "woke up" and started to load the page normally. I'm not quite sure if this helps pinpoint the problem or not, but it does seem like both pinging and forcing the network card to "Look for Networks" act to "wake up" the stalled connection.

While this is still a bit irritating, it's much better than the 4-5 minute stalls I was getting. I'd still be interested if anyone has any ideas to fix it completely (it sounds like it's a common issue too!)
posted by Yiggs at 8:13 AM on November 13, 2012

I apologize if I'm threadsitting, but here's another update:

I decided to keep pinging google.com continuously until it stalled again. When this happened (about 15 minutes after the last stall), I got a "Request timeout" for 24 pings, then it started pinging normally again. While it was returning the request timeout message, my browser was stalling in the same way I described before. So it seems like pinging doesn't necessarily "wake up" the connection.

I also tried rryan's advice, but it didn't seem to make a difference either way.
posted by Yiggs at 9:03 AM on November 13, 2012

Weird. I had this start up on an MBA 2011 a few weeks ago. The solution that has worked for me - YMMV - was from this OSXDaily thread, and was basically 1) note your settings, then delete all your locations in the network preferences and set them up again, or start using them if you weren't before (me), then 2) set your MTU to 1453, citing some old Cisco magick.

Weird, but it worked for me. Just don't ask me to explain it (some crummy storing of a plist maybe?)
posted by cromagnon at 5:00 PM on November 13, 2012

Ah, that'll teach me for not following links in replies. Still, for what it's worth it was the locations step that sorted my problem, not the MTU.
posted by cromagnon at 5:02 PM on November 13, 2012

Huh. Add me to the list who's been annoyed by this for the last couple of months. I just tried the locations fix, and it seems to be working for me.
posted by Runes at 12:54 PM on November 14, 2012

Another update: I've been leaving my terminal window open and pinging google.com continuously. This really reveals the connection drops well. Every so often I'll get a series of ~40 pings that give a "request timeout" (sometimes its 20 minutes between drops, sometimes its more like 5 minutes). It appears to be totally random when they happen, and it doesn't seem to depend on if I'm idling, browsing the web, downloading something, etc. After the 40 pings the connection restores itself, regardless of if I'm at the computer to force it to "look for networks" or not, which makes me think that when I was previously "fixing" it by making it look for networks, I was actually just giving it time to restore itself.

I've tried everything mentioned so far and have had no luck getting this to stop (only improve a bit; sometimes there are periods where it doesn't drop for a whole hour). Worse, I'm totally confused as to what could even possibly be the issue, especially because this only happens on my work connection and only on this laptop...
posted by Yiggs at 3:29 AM on November 15, 2012