nostr:npub1zafcms4xya5ap9zr7xxr0jlrtrattwlesytn2s42030lzu0dwlzqpd26k5 did say local but local for me local is now my extended private network which includes nodes at home and family thanks to Tailscale. Unfortunately last I checked it does not support forwarding broadcast/multicast.

Nevertheless, publishing an encrypted event containing the unicast IP address of clients that could be included additionally as part of the sync could solve the issue of tunnels.

It will allow for self-discovery of Nostr clients over tunnels.