Cannot handle media 'application UDP/DTLS/SCTP' (multiple m= lines?)

[Neil Young]

I have rolled a quick Node JS client for KMS, which fires a "real" SDP offer - taken from a Chrome 92 based little WebRTC app - against a Ubuntu VM, running the latest KMS server, manual installation.

So far so good, but I get a warning with my offer. The warning is right, my offer contains two m lines, but what can I do about this?

Offer:

m=video 9 UDP/TLS/RTP/SAVPF 96 97 98 99 100 101 102 121 127 120 125 107 108 109 35 36 124 119 123 118 114 115 116

...

m=application 9 UDP/DTLS/SCTP webrtc-datachannel

Warning in the log:

2021-09-02T18:11:05,352081 2712 0x00007f7878c9a700 warning sdpagent                  kmssdpagent.c:1557 create_media_answer() <KmsSdpAgent@0x7f786c017ba0>  Cannot handle media 'application UDP/DTLS/SCTP' (multiple m= lines?)

I recall to have read something about a change regarding the data channel SDP in one of the last versions, but I cannot find it anymore. What might be the problem here?