My ping is spiking around 8 am to 5pm ?

Pretty much the same with me. I ruled out everything except an overloaded network. Assuming your modem is working properly and the signal levels are ok, it is likely due to high traffic in your neighborhood due to the stay at home orders. 

The upstream is severly constrained in Comcast's networks so if you have a lot of people doing zoom calls, it can fill up the upstream pipe fairly easily. Total upstream capacity in the Comcast network is about 100 Mbps per second which is usually shared amongst hundreds of cable modems (i.e. neighborhood). A standard zoom call (non-HD) uses about 600 kbps so it can't support more than about 166 zoom calls at once, much less with additional traffic. Our neighborhood has 450 modems on a single fiber node so you can see how it can get overloaded.

You can contact Comcast but they will likely blame your modem or wiring first. Even if a tech comes out, they may not admit to the congestion issues.

yes thats exactly what I thought I contacted comast few times ,but said same things blaming modem and cables  Tthanks for the reply seems like it has no solution..  hope you have a good day