I have a server that I use VLC to transcode RTP video to HTTP video. For http I use the <video> tag to display it on the page. On PC this works perfect but on mobile it doesn't work at all. I see the box with the play icon but clicking on it does nothing. I have tried ogg and mp4 with both theo and h264 and no luck with either.

Something I think might be part of the problem is my site is https but the video is http.  On PC I can see there is a mixed content error but it doesn't seem to cause any issue on PC, but I wonder if that is the problem for the mobile browser.

ETA: Just tried on an http server and that doesn't work either, so I don't think it is the mixed content error.

Run your page thru a XML HTML spec verification compliance check. There's a few sites out there for this.  Some tell exactly what is wrong.  This may shed some light.

What format is the video coming out in? Could it be that your desktop browser has the plugin to render it but the mobile browser doesn't? You're converting RTP to what format/stream?

Im converting rtp to http stream. I have tried both theora/ogg and MP4 with the same results.

There are some examples for HLS streaming which I think I am going to give a try.