Just in case it's a problem you could try clearing your cache before you next join your game. Go to the FG data folder and delete the folder within that with the name of the campaign on it. This is unlikely to be the issue but it's worth eliminating it.
You should definitely contact ISP and explain that you have a peer-to-peer application you are using which the router is interfering with, and that you need them to turn off packet inspection filters on the router.