Possible solution for those have server issues
It seems the UPnP support on some routers including BT's Home Hub is one of the causes.
So if your seeing random server disconnects after playing for some time ~20mins on Bad Company 2 servers try disabling UPnP on your router.
If it helps let us know by voting on the poll and posting the make and model of your router as well as your ISP.
Updates:
* This fix only helps fix for lost connection "with server" not when EA Master servers go down.
* Some may find the following helpful with finding out how to make this change:
http://portforward.com/