Whenever I have persistent disconnecting I problems do 2 things:
1) Reset router.
2) Delete GW.dat and run GW with the -image command line arg.
If that does not help it is an error out of your immediate control.
However dont just assume it is "server side". The internet is not a direct line form your computer to an Anet server, their are a lot of hops in between where things can get messed up. If the above two steps do zilch contact support.