AC 1600 WIFI CABLE MODEM ROUTER Model : C6520

[Prahlad]

Hi,  I am using AC 1600 WIFI CABLE MODEM ROUTER Model : C6520 I am getting very low speed. Can anyone help me with 

changing Channel settings, Quality of service settings, Router logs for faster speeds 

[plemans]

What speeds do you pay for?

What speeds do you get hardwired into the C6250? 

What speeds do you actually get that you consider slow? And how are you testing it? (device you're using, band you're testing on, and website you're using for testing? )

You can find manuals and guides here: 

C6250 | Product | Support | NETGEAR

[Prahlad]

I am Paying for 200mbps

I am testing internet speed in xfinity website 

its 3.8 mbps speed recorded when tested with hard wired 2.5 and 5 ghz 

[plemans]

Do you have a screen snip of the cable connections page and the event logs? 

Also, check the cable for loose connectors, kinks, damaged wire, cheap/old/bad connectors.