Howard Miller

I'm old, too. You just can't tell from my picture

What are you using mod_authz_core for? I assume it's a separate application from Moodle - but Moodle certainly doesn't need authentication within the web browser.

I'm not very familiar with Edwiser except to note that it is well used. However, if you added these plugins at the same time (i.e., it worked before they were installed and does not afterwards) I would definitely delete them to, if nothing else, eliminate them as the issue.

Hmmm.... have you also checked the web server (error) logs? Just in case?

Unfortunately, I'm struggling to think how changing the domain would cause this. Is there anything else that was changed (even if you don't think it's relevant)? Why did you have to do this (for example)?

Two things... 504 is a gateway error. Are you running PHP-fpm? If so, check the logs from that and from your web server to (hopefully) see what's going wrong.

Did you update $CFG->wwwroot in your config.php

That's not the way to replace the URLs (but this isn't what's causing the error). Moodle has a command line tool for that. See https://docs.moodle.org/404/en/Administration_via_command_line#Search_and_replace_text

Switching off file locking is a really bad idea. It could easily cause other problems that are hard to find.

If you want something to try - that isn't so dangerous - consider moving file locking to the database. You need to do that in config.php. The settings are show down in section 6 in config-dist.php.

But... I still think you have some other issue in your moodledata directories.