problem with connect to rustdesk server using LAN ip address

[ytcadsl]

I have deployed a RustDesk server via Docker container on my QNAP NAS.
Devices on the local network can only be controlled by other LAN devices when it connected RustDesk server using the LAN address.
They can only be controlled by WAN devices when connected RustDesk server using the WAN IP address.
I need lower latency, I would like to know how to configure external devices to connect to the RustDesk server via the WAN IP, and internal devices to connect via the LAN IP.