Collabora integration with reverse proxy works like shown in this drawing
as I get from previous post
- assume connection from client to Nextcloud works (https://cloud.domain)
- connection from client to Collabora works (https://office.domain)
- connection from Nextcloud to Collabora doesn’t work
- connection from Collabora to Nextcloud not tested so far
For some reason communication from Nextcloud to Collabora doesn’t work. There might be different reasons e.g. missing/bad DNS resolution, routing or firewall issues or untrusted certificate (from NCs point of view).
PS: it’s more or less pointless to verify connections to the IP and port 9980 - this connection don’t happen in real life and only may help you to troubleshoot. please focus on required connection to https://office.domain and https://cloud.domain obviously both on port 443