Signal levels look fine. Forget the Xbox test or what ever it is. Console test are infamous for being inaccurate.
From a computer connected direct to the DPQ3212 ( a manual reboot with reset button on back will be needed) try:
Windows Key + R > CMD > Tracert xeas.xboxlive.com
and Ping - n 50 xeas.xboxlive.com
Then right click top of window and go to Edit > Select All > Enter Key > Paste into a reply.
That will show any packet loss or latency between your modem and Xbox, and where its happening.