Im running on a wireless connection (WPA-PSK TKIP security) and the same thing is happening to me - my ping is fine until about 1 minute (sometimes less) after joining any server my bar in the bottom left corner slowly rises up into the red and beyond until i disconnect and get a "lost connection from host" message.
Ive searched the forums for possible answers and tryed just about everything, i know my firewall has nothing to do with it as i disabled it and that had no affect, my connection is fine with other online games, browsing the net AND using P2P to download things and im running the latest version of LFS.
My ISP is virgin media and im using a Belkin 802.11g wireless with high-speed mode, model number - F5D7231-4.
I have no idea what to do next and going wired isnt really an option. Hope someone can help as from what ive read im not the only one with this kind of problem.