Moving the stage box to near the console and swapping out the network cable for a known functioning, short cable is the logical first step. If you still have issues after this test, then I would reach out to your distributor for more support.
Also, just to cover all of the bases, be sure you are plugging the cable into the “DSnake” port on the console and not the regular network port. Be sure you are plugging into the “DSnake” port on the stage box and not the “expander” port. You can reference page 16 of the QU Reference Guide….. https://www.allen-heath.com/hardware/qu/qu-24/resources/