Packet delay causing Jitter on line, dropping from some games.

Is this with a WiFi connection ? If so, for a test, does a computer / device hardwired directly to the router / gateway device with an ethernet cable have the same problem ?

With this test, we are trying to isolate this from being either a WiFi-only problem or a problem with the general connection to the Comcast system which would of course affect both. It's a good first step of troubleshooting before we proceed any further.