How to connect multiple site

[friesr]

Have a question on the appropriate way to connect multiple sites.

Currently 3 physically separate sites connected via WireGuard.

Lan IPs:
Site 1 - 192.168.1.x
Site 2 - 192.168.2.x
Site 3 - 192.168.3.x
Etc...

Each site has a unique registered domain for ssl and using nginx with wildcard cert for internal apps.

The challenge is dns and nginx. Using unbound dns and setting overrides to point to the ip address for the other sites nginx loses ssl and apps shows unsecured.

What is the best way to connect the sites together where the remote site can just use the dns of the other domains for their respective resolving?

[meyergru]

I always do such setups with WireGuard. One instance with two peers on each site. Each Site has routes to any of the other two. And in absence of a central DNS Server, I delegate the two remote domains to their respective DNS servers on each local Unbound Server.