Just block explorer.exe with windows firewall - if really needed just enable out going access for internal subnet only.

There is not need for explorer to access internet!

I only allow windows defender, firefox and chrome to access internet in my home computer setup all other apps are blocked unless truly needed.

If you block svchost.exe from internet access with windows firewall, it will block the windows update. Enable it once in a while to allow the windows update to go thru when you feel the need.