I was able to get Roon Remote working between two subnets in the following scenario using 1:1 NAT on a pfsense firewall/router:
LAN - 1.1.1.1
1.1.1.21 - Roon Server
1.1.1.14 - AirPlay device
1.1.1.92 - 1:1 NAT to 1.1.2.2 on LAN2
LAN2 - 1.1.2.1
1.1.2.2 - Roon Remote and Bridge
1.1.2.21 - 1:1 NAT to 1.1.1.21 on LAN1
I also had to add firewall rules to allow traffic from
1.1.1.21 -> 1.1.2.2 on ports UDP 9003 and TCP 9100-9200
1.1.2.2 -> 1.1.1.21 on ports UDP 9003 and TCP 9100-9200
And add Virtual IPs for 1.1.1.92 and 1.1.2.21 (I’m not sure how you do this for non-pfSense router).
With this setup, I can play music on the AirPlay device via the laptop. Maybe you could do the following:
LAN - 1.1.1.1
1.1.1.21 - Roon Server
1.1.1.14 - Roon Remote
1.1.1.92 - 1:1 NAT to 1.1.2.2 on LAN2
LAN2 - 1.1.2.1
1.1.2.2 - Airplay device
1.1.2.21 - 1:1 NAT to 1.1.1.21 on LAN1
I also had to add firewall rules to allow traffic from
1.1.1.21 -> 1.1.2.2 on the ports TCP 80, 443, 554, 3689, 5353 and UDP 554
1.1.2.2 -> 1.1.1.21 on the ports TCP 80, 443, 554, 3689, 5353 and UDP 554
And add Virtual IPs for 1.1.1.92 and 1.1.2.21 (I’m not sure how you do this for non-pfSense router).
There may be other ports that need to be opened for AirPlay, but you’ll have to use wireshark or firewall logs to find out what is being blocked.
John