Hey @nightcobe just a small heads up, before you drive yourself nuts, like I did 
I used Collabora since at least Nextcloud 28 without any issues.
Since version 30.0.3, I have the same strange issues.
See my other forum post
I also tried to check with the great writeup of @wwe to hunt down the issue.
But no luck.
I also use CODE and these two links
worked perfectly fine, but I still get the curl connection timeouts.
I did not have the knowledge or the time to further troubleshoot this, but just so you are aware that this might be a bug and not a config error on your side.