zigbee2MQTT Proxy - to another Home Assistant install

zigbee2MQTT is crashing every 6 minutes on the Home Assistant install

A massively over specced VM.

Had a spare factory restored Home Assistant green.

Moved the zigbee2MQTT to the Home Assistant green

All the devices came back up ok.

Now trying to set zigbee2MQTT Proxy on main Home Assistant to point to the Home Assistant green zigbee2MQTT 192.168.x.x:8080 and getting a 502 bad gateway error.

Does Home Assistant change the zigbee2MQTT port number anyone know what it is?