Hi,
New member and owner of Opal SFT1200!
Came across this post from another thread discussing the Opal and MSC cruises.

I, as OP, attempted to install 4.7.2 Beta and found myself in the same situation, no DNS when connecting via WireGuard or OpenVPN for the clients connected to the router.

I SSH'd into the router and perform a quick ping/traceroute/nslookup while I was connected to the VPN and it worked great directly from the router. Hosts that are only available via VPN responded to DNS resolution as well as ping, no issues.

When looking at the system log I came across an entry that stated:
daemon.crit dnsmasq[14743]: extraneous parameter at line 6 of /etc/dnsmasq.conf.vpn
this was followed by: dnsmasq failed to start

Reverting back to 4.3.24 and, just like OP, reloading from backup, fixed the situation and the VPN is up and running again.
Is there anything that I can provide while testing this to try and help troubleshoot this issue?