Bring the two nonfunctioning nodes close to the main node and restart all nodes. See if they re-establish connection. If so, move the satellite nodes a little further away and see if they re-connect. It is likely a range or interference issue if they work up close but no longer work at a distance.
Thanks.
Had a 4 year system going and this happened.
Bout a new system, it worked for a week, then the same thing happened.
Bought a new surge protector for the main router point thinking possibly stray voltage did some damage .
I will try what you suggested