Turns out the ISP has configured the router to only accept their mesh pods, hence why I couldn't get it working.

A follow up that I have managed to reset the RE705X and while connected to the TP Link WiFi, logged in via the TPlinkrepeater.net and selected EasyMesh. I then tried to complete the set up in...

I have a Heights WiFi 6 HT-178AX router (Rebel Internet) and I'm trying to add the RE705X to the router as part of the EasyMesh system. When I first plugged it in I used the Tether App and it added...