A user marlinhares reports an issue after cloning a Discourse instance to a new server and changing the domain: new topics redirect to the login page. pfaffman suggests checking if the issue occurs in safe mode. Ethsim2 explains that existing posts still reference the old domain and recommends using the discourse remap command to update domain references, followed by rebaking posts. marlinhares confirms the problem was resolved by disabling and reenabling a plugin, but also acknowledges the value of the remapping advice for future setups. marlinhares thanks Ethsim2 for the guidance.
Exited safe mode and as long as I disabled each plugin I retested the functionality.
One plugin was causing the trouble.
But fortunately when I reenabled it the functionality worked ok. I did not know what happened. Maybe a remap on backstage when I disabled and reenabled it.