CONNECTING PROBLEMS DEMIGOD-HELP

Ok i have been playing Demigod alot and i have ran into a problem.   Last week my compter has not been conntecting to the last person that joins a game that i am in. What happens his ping goes to 500-600 ping and will not go down. Everbody else connecting is fine with my comupter. I have never had this problem before so it is really wierd. Before last week i play tons of 3v3 games now every 2-4 games i play it will do that to me. Sometime i will have to leave and rejoin the game to connect better sometimes this works and sometime it dones not. I live in the USA and only play USA games and i have a good internet so i dont understand. I wish i knew what was going on.