Talk Calls - Can't establish a connection

To give some context to the issue, which has been persisting for over 2 months now, my org and I can’t make calls via Nextcloud TALK, it’s inconsistent and only works randomly at times.

Strange behavior: I’ve noticed that some of our users have calls on a daily basis and it works just fine. On the other hand, I can’t seem to establish a Talk call connection with some users, but can with others.

The main problem lies as follows: There is no single error log, that points to Talk, to failed connections, or bandwidth drop of Nextcloud. There is nothing that has pointed me in the right direction just yet, as any time I try to replicate the issue by calling and not being able to get on a call, when I follow Nextcloud ground logs I get nothing but expected behavior.

I’ve manually upgraded the php version and all of the modules, I’ve upgraded the Nextcloud versions to newer/recommended ones, I’ve manually upgraded our MariaDB Nextcloud database, I’ve even upgraded the instance where Nextcloud is hosted, giving it way more resources (almost double, which significantly improved the overall performance and it’s noticeable how much faster everything runs), but it just won’t fix the Talk call error.

We have a STUN and TURN server, but that also isn’t helping.

Checking all of the Nextcloud forums and community posts didn’t help me find what might be causing all of this, my last option is to ask for help in this forum.