Nextcloud <-> Collabora communication

How does the communication between Nextcloud and Collabora flow?
I have Nextcloud on and Collabora on and from home network is working fine. I can open .odt and other files in Collabora and edit it. If I try the same thing from work network it doesn’t work. At work we have closed outbound connections in non common ports (42028 is one of them). Access to Nextcloud is working, I can view images, .txt files… but I can not open .odt files. When I try to open .odt file, after couple of moments I get “connection timeout” error.

I would expect that I (client) would be always connected to Nextcloud ( and that Nextcloud would be connecting to Collabora server (

Your Collabora Server must also be reachable from the Client. The closed port at work is the reason you get the timeout. You may ask them to open it (unlikley), or configure another port on your collabora server (not sure how easy or difficult that would be).