@TomsFreitas an idea is to then check cloudron server logs.
LDAP logs are suppressed by default. For this:
Edit /etc/systemd/system/box.service
Find the Environment= line. Change "DEBUG=box:*,connect-lastmile,-box:ldap" to "DEBUG=box:*,connect-lastmile"
systemctl daemon-reload
systemctl restart box
Now, maybe something appears in /home/yellowtent/platformdata/logs/box.log .