yeah people seem to have been having the same sort of problem where its only effecting certain computers at somewhat random times even if they are using the same internet source. because of this i dont think its a client side issue personally, i doubt this is something SE would easily overlook either. it might have something to do with a variety of ISPs. to be honest, the game league of legends has been having an almost identical issue it seems for a large amount of people, so if its an overall network issue, it might explain why this has not been solved yet