I too was concerned about just relying on wifi connection so I have investigated and added a ‘wired’ solution for emergency use.
Wifi router is an Apple airport express.
I’ve installed a small netgear Ethernet switch with the QU and the Airport Express connected.
Then I use an Apple lightning camera connection kit powered by a standard Apple IPad power supply, with an Apple USB Ethernet adapter attached with a short cat 5 cable to the Netgear hub and a non-Apple 1m lightning extension cable to allow the iPad to sit on top of the rack.
With the iPad in Aeroplane mode I am able to successfully connect to the QU and control everything as over the normal wifi connection but via the Ethernet connection.
I’ve also tested the connection direct into the QU, without the netgear hub or airport express involved. In this mode you need to switch off DHCP on the QU.
All seems to work fine though.
Pete