Corosync Packet rejected


I want to create a corosync cluster between two networks(in my case they are called rmg and lan) separated by an turris omnia. They are different subnets and different firewall zones in the omnia router. In the zone configuration forwarding between the two zones are allowed.

Since the upgrade to corosync 3 this seems to not work anymore. In corosync I use udp unicast as a transport protocol but according to the corosync logs it gets rejected by the omnia router:

corosync[6220]: [TOTEM ] Packet rejected from is the omnia router.

Normal udp traffic works (i.e. opening an udp port on one host with nc -u -l -p 9090 and connecting to it from another host nc -u buero-hv-02 9090.

Any ideas what I could troubleshoot or try in the settings in order to allow this kind of traffic?