Don’t bother trying to connect your Horizon box to your wifi, or even using an ethernet cable directly to your connext box.
Connecting your Horizon box to your LAN does nothing useful at all*. It won’t use that internet connection for replay or the guide text etc. The Horizon box needs its own internet connection else you’ll get errors such as 2020/6010 and an “offline” light on the front panel.
If you’re getting TV pictures but no replay it’s one of two issues. Either (1) UPC have messed up and provisioned your connect box whilst accidentally disabling your Horizon box or, more likely (2) you’ve connected the Horizon box to the “wrong” socket in the wall. You may need to use a splitter. To test … disconnect the coax cable from the back of your Horizon box and use the one currently going into your Connect Box. You’ll lose internet, so this is just a test, but you should find the Horizon box starts to work. That proves the issue is (2).
* Connecting your Horizon box to the LAN is only useful if you, for some weird reason (because it’s crap) want to use your Horizon box as a DLNA client.