hbbs sends local network IP instead of WAN IP, causing connection to hbbr to fail

[doragasu]

I have deployed hbbs and hbbr on a RPi board at home, and installed RustDesk on several machines on the local network.

When I run the client on the same local network everything works great. I can connect to any machine, no problem. But if I run the client from outside my local network, connection to hbbs succeeds but connection to hbbr fails, even though all related ports are open and NATed on the router. I have been diagnosing the problem using Wireshark on the machine running the client doing the connection, and the problem is the connetion to hbbs uses the correct global IP address (e.g. 37.123.123.123:21115) but the hbbr connection uses a local IP address (e.g. 192.168.229.32:21117).

This is a Wireshark capture taken on the client and showing the problem:

At first, I thouth my problem could be related to this: NAT Loopback issues. But since I'm also running pi-hole on the server machine, I tried method 2 without success, same behavior.

Also tried manually starting hbbs with -r WAN_IP_OF_HBBR, but again it didn't work. And I'm out of ideas.

How can I make sure hbbs sends the WAN IP instead of the local IP? Is this configuration not supported? Am I missing some config to achieve this?