Using the Xfinity rented modem, my promised gigabit speeds are nowhere to be found. My speed actually fluctuates and flatlines with no device input or activity. Have done the standard service recommendations of restarting the modem with no change. To be honest, got higher and more consistent speeds on their outdated modem. What gives?
What is your speed with the LAN cable from the computer plugged directly into the modem? Make sure you have a 1GB LAN interface in the computer.