-- Audio and Video codecs

From the list of available audio codecs, please deselect all except 'opus/48000'.
From the list of available video codecs, please deselect all except 'VP8'.
You can make this change via the interface of Jitsi:
-> Jitsi-Tools-Options-Audio-Encodings
-> Jitsi-Tools-Options-Video-Encodings

It is recommended that all the participants of an audio/video call to use the same codecs.