Herelink v1.1 ethernet tether to ground station


I’ve had a scan through the forum, but haven’t found this exact use case and wanted to see whether it was possible.

I have made up the JST GH to ethernet cable per the specifications in the other posts and essentially want to connect it to a pre-existing router setup on the ground that shares a LAN with a computer that will see video and control. The goal is to have a tethered drone with no wireless interaction. On plugging it in, the router cannot see the herelink at all, the port LED lights up but has no activity. Is there something I am missing or is this not a possible configuration?

Many thanks