Intermittent connection and 1/3 speed of 1GB plan

Hello all,

I'm at a loss on next steps so turning to the community for viable solutions.  I've had two issues since moving into a new home and signing up for a 1GB plan.  Intermittent connection issues which are most noticeable on video calls for work and gaming online.  I am also pulling on average around 275-325 mbps with this 1GB plan.  

Currently using a CM1200 Netgear modem DOCSIS 3.1 

Actions taken so far:

• 3 different Comcast Techs have visited so far
• Replaced cabling from the tap(pole) into my house and new cabling inside the house as well with new connections
• Tried two different brand new modems Netgear CM1200 and Arris SB8200
• Connected modem directly to new cable coming in from pole to elminate any issues inside the house
• Connected multiple PC's with 1GB NICS directly to modem and have similar speeds
• Comcast tech mentioned submitting a ticket for a line crew to come look at the line on the poles in the area and the hub to ensure ability to support 1GB.  In my most recent call to support they don't have a record of this and there are no next steps in place to resolve my issue
• Replaced ethernet cables to ensure no bad cables