I bought RE330 to extend the guest network from Archer C80 router with the same network ID and password.

Very disappointed to now discover that the router can't share the guest network with the RE using onemesh, only the main one.

The question now is there another way of doing it without creating a 3rd network called <(mainnet>_EXT?

Seems like an obvious and reasonable expectation which many people have.

Maybe easymesh can do it?