Arris says upstream Power levels should be 45 to 51

Here is the chat with them:

Seshan R (5/25/2020, 1:15:13 PM): The recommended power levels are the same for almost all Arris devices. your upstream power should always be between +45 and +51
Seshan R (5/25/2020, 1:15:22 PM): By having the values in less than that, your device will have interrupted connection, slow or no connection at all.
Seshan R (5/25/2020, 1:15:42 PM): In your case, your coaxial cable is sending poor signal, and is affecting the device itself to communicate properly, we would recommend that you contact your service provider to make the appropriate adjustments to those levels for you.

Arris is wrong !!!

Again. THEY ARE WRONG !! They are passing the buck !! Only the Comcast plant / engineering specs matter;

Are you actually having any problems or just focusing on the stats ?

Nah. That's on your end / LAN / home network..

Yes, I have been paying for 300 MBPS but router is always saying 100 (91). So I called xfinity to look at the incoming and they came here and said everything was right . It was not until I hard-reset my modem and connected my one ethernet directly to my computer that I saw the 300.  I think after bugging them they modified something. Then when I replaced that ethernet with a connection to my google nest wifi router I could only see the same old 91!

I have had the same problem with the last two Arris modems I get the same run-around.  Arris says they want 45 to 51, xfinity says they can't change what you have.  Yet, Xfinity says the Arris modem is compatable with the system.  And the Arris modems keep failing.