Hi,
Just checking on the status of the issue. The temporary SSH account I created for your investigation is scheduled to expire on July 21. If you haven't had a chance to access the server yet, please let me know so I can extend or recreate the account if necessary.
As mentioned previously, the Laravel API is responding correctly over HTTPS, and the issue appears to be isolated to the Flutter app when using the domain instead of the IP address.
Please let me know your progress. Thanks!