First check your MIDI settings (p. 68 in the manual:
https://www.allen-heath.com/media/Qu...-AP9372_10.pdf ).
The protocol itself:
https://www.allen-heath.com/media/Qu...tocol_V1.9.pdf
Before attempting to send something, I recommend record changes from Qu. So use it as input for some track, start recording and do something on the mixer. That activity should produce MIDI events.
Note that REAPER does not interpret NRPNs as such, so you will get a series of CC events. Also start with USB connected MIDI, Ethernet it sticky.
Once you have success, you already can "record automations". You can also separate specific actions as use them to "compose" automations.
If you have some programming skills, you can make simpler/advanced processing with JS and/or CtrLr.
PS. I have operated Qu in another direction (Qu controlling DAW) and only remotely.