Collabora Not Connecting

I’ve installed Collabora on NextCloud, and the app is appearing but it remains stuck saying “connecting…” for a very long time, before giving up as unable to connect to the file.

How would I go about diagnosing and fixing this problem?

To complicate matters, I’m running this on a clustered setup. So I have multiple nodes that serve websites (where NextCloud is one of these) and these all use a shared storage server for data / databases.

I’ve dedicated a storage server specifically for NextCloud and that’s where I’ve also installed the Collabora docker image.

I followed the instructions and set up a reverse proxy (Apache) that forwards to the storage server (though this has been duplicated to each of the nodes, so that they all can access the Cloud storage server with Collabora running on it).

In order to get this working, though, I had to make collabora.domain.tld publicly accessible. I’d rather this was not the case, as you should only be able to use our Collabora instance through NextCloud. Is this a DNS issue with the docker image?

Could I keep things strictly internal by editing the “/etc/hosts” of the docker image? (How would I do this, as this is the first time I’m dealing with Docker in earnest and don’t know what’s what with it yet?).

Collabora itself is coming up just fine within NextCloud. It just seems to be that Collabora can’t connect and access the files on NextCloud.