Thanks for that. Sadly, that also didn't work. So I have tried:
- the original IP (192.168.1.1)
- the new WAN IP as seen by my UniFi Gateway (10.79.x)
- the default IP (192.168.8.1).
The 10.79x address just routes me back to the Unifi console (my LAN is coincidentally also configured on a 10.x network), but both the 192.x addresses are unreachable for me.
In terms of connections, the Ethernet 1 port on the X3000 is connected to the WAN port of my UniFi Gateway, which is the only connection combination that worked.