GT5 is very tough to handle when it comes to connections. You really need a good connection to hold it online. When I first got it, I couldnt stay online for more than 5 minutes no matter what room I was in. I was on wireless and still am, but I had a 100Mb/s router. Now I have a 600MB/s router and Voila, the problems were gone. Didnt need to port forward anything, or whatsoever. Also, my connection is private(password protected). Maybe upgrading router or modem could help, at least it helped me a lot.