@Yamakazi It’s all explained in the man page I posted:

–mcast-rdv-address address
Uses a non-standard multicast address for the control (rendez-vous) connection.

By default “mcast-rdv-address” is the Ethernet broadcast address if “ttl” is 1, and 224.0.0.1 otherwise. …

So multicast control connection should be on address 224.0.0.1 I suspect! And then:

–mcast-data-address address
Uses the given address for multicasting the data. If not specified, the program will
automatically derive a multicast address from its own IP (by keeping the last 27 bits
of the IP and then prepending 232).

Means 232.x.x.x if I don’t get that wrong.