Hello darshan!
First and foremost I would like to thank you for your response.
I found the solution by adding a port to my “Server Name” in TrueNas Scale.
For example if my domain was “collabora.mydomain.xxx” then I added the port “:443” which I found to be the solution in another forum.
Im not sure if this is the right way to do it but it works at this moment.
server_name is “collabora.mydomain.xxx:443” and this removed the port “:9980” that was automatically added by collabora when writing it into my nextcloud office configuration.
Best Regards.