@AndrewPM 

When the issue happens, have you opened up Kasa to see if the switches show up normally or show local only?

Google Home relies on the switches remote connection to work.

They show up and work in the Kasa app when I use my phone not connected to my local network (i.e. on 4g and not on WiFi).

I also run commercial network hardware for my home network (software / networking guy) and I can verify through my network and wifi management software that all switches/outlets are 1) connected to an access point 2) which access point 3) how much data they are sending/receiving and from/to where and lastly 4) their connection strength. All those look great. There are also no firewall rules blocking their communication because I can see their traffic exiting to the internet.

@AndrewPM 

I would probably get a hold of our smart home team here: Kasa.Support@TP-Link.com

They should be able to see if there may be any logs or clues on what may be going on.

@AndrewPM 

my wall plugs stopped working but my light switches work