Problem with WiFi Internet Crashes

I have a Comast Modem/Router, with wifi being on. I also use Insteon, which has been absolutely bulletproof. How I have set up to systems is as follows.
I use 2 ethernet jacks from my Comcast router, one goes to Smart things Router, the other goes to Ethernet switch, and from that I go into Insteon router. and several IP phones.
Generally, the 2 systems work perfectly for 2-3 weeks.
Then I will get horrible Wi Fi and everything disconnects and then loses their signal.
I have 8 Samsung mesh routers, that crash and then try and reconnect. The only way I get things back online is to shut everything off. Let it sit for 15-20 mins. Then I slowly bring up Comcast 1st, Then the Samsung routers, and the Insteon router. Then things are good for a week or two, and then life crashes again. I can not find an answer to why systems crash, generally it is when no one is at the house, and things are quiet Any suggestiosn?

Sounds like the Router is dropping things, why don’t you try getting an external router and just using the comcast modem as a modem. Do your mesh routers have that functionality?

I have replaced Comcast router twice, thanks for idea tough