graphowl
Generic advice:
I'd redo your set up if possible or at least set up another device with the same set-up. If you don't have another phone, maybe a PC will do.
Your phone could have a bad configuration file on it. Careful of thinking 2 config files are the same -- 1 is newer -- and copying that 1 to the new device so then you conclude it's not the config. Double check versions of the client and server.
Make sure both environments are the same: same WiFi network, dns server, vpn, etc.