Failed to create peer connection: createDataChannel on a null object reference

[mt131]

Browsers and versions affected

Description
in test server it is ok but in my own server it has error:
Critical error: Failed to create peer connection: Attempt to invoke virtual method 'org.webrtc.DataChannel org.webrtc.PeerConnection.createDataChannel(java.lang.String, org.webrtc.DataChannel$Init)' on a null object reference

Steps to reproduce

Expected results

Actual results