Help With XFinity Problems

I ran a brand new Quad Shielded Cable from the outside connection straight to the Modem and now I am getting 45-46 DB Down and 39.5-41 DB Up so modem traffic looks good but still getting Critical "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing" and Warning "MDD message timeout" in my event log and an unstable connection. Been on hold for 30 minutes waiting to talk to a human at Xfinity to ask them to ping the modem and tell them it 100% is on their end as it is a brand new Quad Shielded cable run from their termination to my brand new Modem.