For the longest time I could not get Collabora working in Nextcloud. It would connect then disconnect shortly after. Once I fixed that issue and it would stay connected but would fail to load documents. Both of these issues were actually the same issue.
In Collabora app settings “Server Name” needs to be set to whatever URL you are using to connect Collabora to Nextcloud. So for me since I am just using IP Addresses it needs to be my TrueNAS IP Address.
I really wish these tool tips in App configs were more descriptive. In this case it just says “The server name for Collabora.” Very helpful really, every one of these I have ever looked at is not any more descriptive then the title of the thing it is describing. In what world would someone think based on the description this actually meant the URL or domain of the Collabora server. I originally just named it “Collabora”.
Hopefully this saves at least 1 other person hours of there day.