I cant play more than 20 - 25 minutes online in LFS

25 mins after joinning any server, LFS shows LAG captions over the rest of the players, and then, all disappear and only the LAG captions remain.

The rest of the players can read my chat and I can read them, even I can see when someone does fastest lap ...

If I quit the server and rejoin all works fine ... till 25 mins pass

any ideas ?

I close all my programs before playing (firewall, antivirus, etc etc ...)