Internal Server Error connecting to Collabora

I have Nextcloud 13.0.8 installed in a vps as a snap. I have Collabora installed on a server at a different location in docker on Ubuntu 18.04. I have setup the SSl cert with Lets-Encrypt and all appears to be ok. When I try to open a document I get a ‘Internal Server Error’. I’ve checked through all my configurations and I can’t find the problem. Is there a way to check the Collabora docker installation? Is there a demo Collabora install I can connect to and test? I can’t find anything relevant in the logs that I’ve looked at. Any help to get me started will be most appreciated. Thanks Ian

If your docker container is up and running.
(Check docker ps)
If you can access your reverse proxy without issues, let’s say,

And you get a correct ssl page (maybe an empty one).

Then the issue may be the way you run the docker image.

Check more details at,

Sorry for the delay in replying. Thanks for the help. Problem may have been a delay in the DNS propagation. Everything is good now.