C1100z issues

Hello, I got centurylink 40m line and a c1100z modem. I was using q1000z and games and torrents were fast and good no issues. I got my c1100z and when playing Xbox on wireless it’s laggy and have to quit the torrents don’t seed like they do with the q1000z. I opened the ports up for torrents and on Xbox but it’s horrible. Newest firmware updates so my question is this is the modem bad because it’s not like the old one performance wise or is it not made for my line. Thanks john