@Yobh 

generally when Ethernet is just below 100 the first thing to check is the cables and the connectors. Do look at the connectors on the router and modem for missing or bent pins since you tried different cables.

Are you running a VPN?

Anything in the USB ports such as a backup drive such as Time Machine?

try changing the Firewall settings.

Is your WIFI speeds much higher on the AX11000

Can you try a different PC?

What mode is the Charter in and what mode is the TP Link router in (Charter in bridge mode and AX11000 in router mode or Charter in router mode and AX11000  in AP mode)?

  @ArcherC8 
Hello,

No VPN
No USB devices
No changes to the firewall
WiFi speeds match my hardware speeds
I used a iPad and got simular results
Charter in bridge mode and AX11000 in router mode

I have tried using the ax11000 in AP mode with the their new route in router mode. With their router I get the speeds I should, around 450Mb.
Currently, I have both routers in place. Yes, I am double natting the devices. The new Charter(Spectum) router => my AX11000 router.
Its not ideal but it does work.

  @Yobh 

Have you tried different Ethernt ports on the router and the Charter Gateway?