Trouble with 50mb

[angy141]

Firstly I know hardly anything about routers modems etc, except the very basics I had 50mb broadband installed on Thursday upgraded from 20mb .I have noticed that the internet doesnt seem as fast and my son says every hour or so he gets DNS error come up on PS3 .Also when I logged on to router it says error on all LANs and shows picture of broken connection.I can still go on internet and he can play games but we just think it was better with 20mb.I got the 50mb because my son is getting COD modern warfare on tuesday and he wanted a fastest that he could get (he is paying for it) but its just these issues we have with it and none of us are fantastic with computers so can anyone give us a quick fix or should I contact Virgin .