When I start Orbot up on my phone in VPN mode, it gets stuck just "starting". I've left it for up to 10 minutes but it ends up going nowhere. I've tried using bridges and changing my TOR identity, but to no avail. Weird thing is though, sometimes it does end up connecting fine, at the same wifi, using what I believe to be the same settings. Is there anything that could be different that's preventing me from connecting?
Orbot looks hangy somtimes, so you either examine it's logs - it will tell you the reason, or you're cleaning the app data and sometimes reinstalling it completely. Also it can be because of firewall rules problem - it popped out from time to time: it was related to the firewall cli binary included with the app and sometimes with the resulting ruleset - I was facing this on Android 6, but it has reappeared rarely from time to time. Also keep in mind that mobile antiviruses can ruin your day just like their desktop twins.