Wireless Streaming to VR Headset With On-Premise Equipment

Unfortunately, I won’t be of much help. I’m not familiar with WebRTC and may steer you in the wrong direction.

I believe that WebRTC signalling is based on websockets and you may be able to build your own server.
https://www.webrtc-experiment.com/docs/WebRTC-Signaling-Concepts.html

There’s been several other implementations using cloud-based servers. For example this one:

There was additional discussion here:

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As far as I know, no one was able to implement an on-premise private signalling server. I’m not sure if it is difficult.