Android mobile app error

Cannot connect via Android mobile app to my self-hosted VW instance.
When I input the email address to log in, I get the following error immediately/instantly (no hesitation or delay before this pops up): “Exception message: Connection failure”
I can connect to the instance successfully via Tor Browser on Android, so I know it is reachable, but this is not a satisfactory way to utilize the service.
Please help!

Hard to tell what could be the cause of the connection failure. Can you check with something like SSL Server Test (Powered by Qualys SSL Labs) if you set the web server up correctly? (It might not be reachable via IPv6)