Technicolor Xfinity *HELP*

So Ive had this problem for months on WoT so I stopped playing Xbox for a while I came back hoping it would be fixed but I was not then I realized I was getting disconnected from black ops 2 trying to play league play etc. btw I just want to play world
of tanks Xbox but it won't work I can't play 5 games in a row without getting a game error then getting d/c from live, I called comcast he tried to open ports and what not it did not work at all I mentioned something about firmware updating he said something
like I can't remember but he said everything was working fine but nothing changed I got d/c first game I tried after so he told me to order a new modem which I thought would be different than the technicolor but I got the same one, I hook it up and I tell
the guy my recent issue he tells me to put a DMZ on my xbox ip so I do it works for a day in a half then I started to get d/c from WoT again same place I started. No progress so a brand new modem did not work DMZ didn't work if it did it was only 1 1/2 day
then last night I tried turning off fire wall did not change so I just put it back on at this point I do not know what to do HALP

:)

 

getting disconnected from xbox live while playing multiplayer game

I have the Xfinity Technicolor TC8305C

 

100% Network Packet Loss error

It is a Cable modem. Xfinity "Technicolor" is what is says.

 

Greetings JR smith!

Did Comcast replace your gateway (Technicolor 8305C) with the same make and model, as your current one?