They are using a deamon called SmcRoute to route multicast packages and iptables rules to increase TTL. However SmcRoute does not exist on our router. I got the impression that Avahi would act more as a repeater (hence reflector), rendering all other configs obsolete. If it could repeat multicast on adjecent networks that would be it.
An interesting thing that may be nessisary though:
Code:
ip link set wgs1 multicast on
If this is not enabled on the interface its not going to work. On the router side you could just execute above to enable it (until next reboot / restart of wgs). But what about the other end? You have far less controll over, say Android, Wireguard interface settings. After all this trouble, how to make Android send multicast over vpn?