New Cam on existing cable run

[mpunt]

Suggestion to maybe see if it's a POE excessive voltage drop on a long (maybe CCA) cable that's implicated:
If feasible - temporarily power the new camera on the not-working old cable with a 12v power supply directly at the camera.
Ethernet is much more forgiving of cable resistance than POE.

Pretty much the only thing we didn’t try. Will do that next time I mess with them. Thanks