I have had sporadic network problems at my client site. On certain days, it seemed like my network connection would partially drop every 10 to 15 minutes. By "partially", I mean that some connections would stay up with no problem (like to an IRC channel, or connections to Google), but everything else would disappear, both locally and on the internet
My laptop worked fine on other networks, but it didn't work on any port at the client. But this was only on certain days. For a while it seemed like it was just on Tuesdays. The only way I could get it to come back was to either restart NetworkManager or physically unplug and replug the ethernet cable.
With a little help from a number of online friends, I figured out the problem was an IP address conflict. Switching to traditional ifup/ifdown, the log showed me exactly what was happening... the address DHCP was handing out to me was already taken by someone else. (00:08:02:8a:1b:04, I'm lookin' at you. Stop hard-coding your ip in the DHCP range!)
Thanks to advice from the enterprising Matt Hunt, I used GNU Mac Changer to change my MAC address so that DHCP would hand me a different IP address, and everything now works fine.
