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

MoodleBox disk image for microSD card
Version: 3.12.0
Moodle version: 3.11.1 (Build: 20210712)
Size: 733 MB
Date: 11 Jul 2021
Release notes: on Github
SHA-256: moodlebox-3.12.0.sha256