Webclient do not follow `-r` options to find `wss://` location

Describe the bug
I'm hosting rustdesk-server on Synology, and add reverse-proxy 18302/18303 to 21118/21119 port. and then I can connect to my synology server with https://domain:18302 on https://rustdesk.com/web/

But the web client complains that it can not connect to relay server:

Failed to connect to relay server, wss://192.168.83.42:21119

but I'm already tell hbbs to use 192.168.83.42:18203 for relay server:

services:
  hbbs:
    container_name: hbbs
    image: rustdesk/rustdesk-server:latest # Please change this to rustdesk/rustdesk-server-pro:latest if you want to install Pro.
    command: hbbs -R 192.168.83.42:18302 -r 192.168.83.42:18303
...

So, How could I tell hbbs that the real wss:// relay server is on 18303?

Describe the environment

• Install environment: Synology Container Station & docker compose
• If available, the docker-compose.yaml file:

services:
  hbbs:
    container_name: hbbs
    image: rustdesk/rustdesk-server:latest # Please change this to rustdesk/rustdesk-server-pro:latest if you want to install Pro.
    command: hbbs -R 192.168.83.42:18302 -r 192.168.83.42:18303
    environment:
      - RUST_LOG=debug
    volumes:
      - ./data:/root
      - ./config:/.config
    network_mode: host
    depends_on:
      - hbbr
    restart: always

  hbbr:
    container_name: hbbr
    image: rustdesk/rustdesk-server:latest # Please change this to rustdesk/rustdesk-server-pro:latest if you want to install Pro.
    command: hbbr
    volumes:
      - ./data:/root
      - ./config:/.config
    network_mode: host
    restart: always

# Because using docker host mode
# Just in case you forgot the ports:
# 21114 TCP for web console, only available in Pro version
# 21115 TCP for NAT type test
# 21116 TCP TCP hole punching
# 21116 UDP heartbeat/ID server
# 21117 TCP relay

No source files or tests are named. Start by tracing hbbs handling of the -R and -r options and how the web client derives its wss:// relay address; verify the configured relay port 18303 is reflected in the generated connection endpoint.