I setup the current version of MoodleBox on a Raspberry Pi.
I used my smartphone to connect to the Raspberry Pi Hotspot.
I can successfully access the Moodle Site using a browser, but can not connect using the Mobile App.
I replicated the issue with an Android tablet.
Other people have had this issue since an upgrade . See https://moodle.org/mod/forum/discuss.php?d=424353