janusvideoroom.py example doesn't work for H.264

If I try to use H.264 as encoding in janusvideoroom.py, by making line 19 to be False, I always get HangUp(sender=7135993183297719, reason='ICE failed') in the console output. Errors in Janus log:

• [ERR] [ice.c:janus_ice_check_failed:1760] [1786197890426270] ICE fa- iled for component 1 in stream 1...
• [ERR] [sdp-utils.c:janus_sdp_get_codec_pt_full:693] Unsupported codec 'none'

Gstreamer 1.18.0 is installed in a Ubuntu 20.10(yes I just downloaded the Beta :) ) docker container and janus gateway is installed in another docker container. The example works smoothly using VP8.

I also attached a log file for the janus gateway,a capture file taken from Wireshark and the output for janusvideoroom.py

gstwebrtc-to-janus.pcapng janus-log-stdout.txt janusvideroom-output.txt

P.S: I am sorry if this is not the right place to ask, but I tried all day long things that did not work