THX for your help, and thx for the hint with udp, i think this is the problem, since the needed UDP traffic is not forwarded within these subnets.
From Cisco i remember to configure ip helper addresses, f.e. UDP: 32410, 32412, 32413, 32414.
ip helper-address 192.168.1.187
ip forward-protocol udp 32410 etc…
is there something similar on pfsense?