Second WG issue I have to report today, this might not be visible yet since 23.7.6 didn't require a reboot. No reports on Github yet.
Two WG configurations on different FWs - connecting using IPs so no DNS in play - gateways don't come up post reboot. Need to go into the GUI and disable/reenable Wireguard.
Tried reverting only opnsense to 23.7.5 but that didn't help, so I reverted os-wirguard too and now the GWs are starting fine.
I have the same issue on 3 boxes on 23.7.6, didnt need to disable/reenable wireguard service, but i clicked on the restart buttons for each connection on the main gui page. That got the connections working for me.
Same issue here as well.
There is a bit of support https://github.com/opnsense/core/issues/6934 and a bit of a bug at play https://github.com/opnsense/core/pull/6937
Most people should get their setup into working order when following #6934. All of this (except using VIPs) appears to be a misconfiguration.
Cheers,
Franco