H264 is disabled in the meet.jit.si config for both P2P and JVB case. Since you have a self-hosted instance, you can just use that and control the config yourself.
I was testing with meet.jit.si and saw the following log:
I JitsiMeetSDK: [modules/xmpp/JingleSessionPC.js] JingleSessionPC[session=P2P,initiator=false,sid=c6b4ccb52563] Switching video codec from vp8 to h264
It is very confusing - do you know why it logs H264 if H264 is disabled ?
Note: I am running with SDK 6.2.2 not latest.