Mynet 600 causing cable modem problems?

I’ve been experiencing problems with latency and spikes in my internet service. Resetting the modem and/or unplugging the cable would solve the problem for a little bit until it returned. Called the provider (Comcast) and they said everything looks fine on their end.  I got rid of any unneeded splitters and even replaced a few others.  The problem is still there.  The download and upload power levels are constantly running high and have tremendous movement throughout the day.  Last night while the levels were high again I decided to plug directly into my PC from the modem and bypass the router.  Turned the router power off too.  This morning power levels are where they should be and are stable.  I plan to let it stay connected like this for a day or two to see if there are any changes.  But could the router be causing the modem power levels to spike like that?  Is this possible or is it coincidence?  I can’t really locate the router to another room since it needs the connection from the modem obviously.  Is there a setting or something that I should change?

Hello, did you check if you have the latest firmware update?