Ok I'm pulling my hair out over this one. We have a wireless network with many clients all working well except two Ubuntu clients running 10.10 that can't access the internet via a browser at the same time. They can both still ping, use Skype etc but can't browse.
As soon as the one that can browse exits the network browsing returns for the other and vice versa. As ping and Skype was working I assumed some kind of DNS problem but moving over to OpenDNS didn't solve it, nor did restarting networking or using wired rather than wireless.
We also switched out the router, and it still persisted so I'm sure this isn't a network issue. The two clients are both laptops and work fine together on a wireless network at another office (which we don't control).
I'm thinking something must be cached from the other network they both use that's causing this but have no idea what.
Does anyone have any ideas? I just don't know where to go from here.
Best Answer
Difficult to say, given the limited amount of information available. Here's a couple of random suggestions.
Check that proxy settings are correct (similar to working laptops).
Check that Proxy Auto-Discovery works the same for your two browsers, as it does for browsers on other laptops on the same network. Auto-discovery happens via DNS in Firefox, Internet Explorer supports both DNS, DHCP (via an INFORM request for option 252) and Group Policy distribution of proxy settings. (Maybe IE supports one additional method, I can't recall at the moment.)
Use a sniffer like tcpdump or Wireshark to figure out exactly what is going on. If you're not sure how to interpret the raw packets, the additional information might be useful to add to this question.