Nighthawk CAX80 slow speeds on Xfinity

[proscancomcast]

I am from West Michigan and have Precisely the same problem. I live in a suburban home and do NOT have any splitters or bad coax 

My provider is Xfinity and have had both Netgear on this (they say it is Xfinity) and Xfinity on this and they say it is a bad CAX80.

I got on Amazon and purchased a new CAX80...installed it and had it provisioned by xfinity.   Exact same results on two different PC's 

I pay for 1.2G and I get max 550.

I have had a technician come to the house two times and they say they do not have signal problems to my modem.

An "outdoor" technician checked my underground pedestal and connections..He told me that he Got 1.5G and 100M when he check it from my port. 

Sent the duplicate modem back...installed my old CAX80 and ....guess what?  SAME PROBLEM!

WTF?

[FURRYe38]

Please post a copy and paste of the modems connection status page.
Be sure your using good quality RG6 coax cable up to the modem. 
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router?article=24311
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html

Be sure your using a good quality LAN cable between the CAX80 and your PC. CAT6A UTP if your connecting to a 1Gb LAN port on the CAX80. CAT6A STP if your connecting to the multi-gig port on the CAX80. 

Be sure your ethernet drivers are updated on the PC. 

[plemans]

How are you testing speeds? 

Wired? 
Wireless?

Whats the device you're testing on? 

Do you have IPv6 enabled?

What site are you testing on?  have you tried different servers on that site?