PoE Intercom with 4 wires?

Howdy folks. I've got an intercom I'm trying to get working. I'm attempting to use 4 wires leftover from our access control system.

The run is going through about 200' of conduit that I can't get a fish tape through due to multiple bends and what I assume to be a sleeve about 180' in since I can't get past that point from either direction.

So using those 4 wires, I connected the wires to the WO/O and WG/G at each end. WG/G should be supplying my PoE power, and the intercom lights up, so it's getting power. But I'm not getting an IP for the intercom.

Any suggestions on how to make this work? New conduit and wiring isn't a solution and I've only got 4 wires to work with.

Thanks!