I have 2 versions of OS-Ticket on trial:
1 - Cloud-hosted: It all works
2 - Self-hosted 1.15.2
NOTE: I have set up Gmail to accept 'less secure app access.
What did am I missing?
Presuming that you checked the settings between the two different sites already to make sure that you are comparing apples to apples... then it stands to reason that the likely culprit would be the local server firewall / or your network firewall.