Setup Help with CollaboraOffice

i need help to setup nextcloud with CollaboraOffice

currently I get endless loading when I use collabora

I think this is a configuration problem
but i dont know how to configure collabora with nextcloud
i tested some stuff but nothing works for me
i hope that anyone her can help me

this is my steup:

nextcloud and collabora are running on my homeserver without docker.
im using my sophos firewall with dyndns and virtual webserver for ssl

nexctloud https - * | http -
collabora https - * | http - (i cant use 9980 because the firewall uses this port)