Unable to open documents. Connection timeout

I am uanble to open documents with collabora. The screen displays the loading cirkel until the message “Well, this is embarrassing” appears.

wsd-00027-00040 17:24:20.743077 [ docbroker_001 ] ERR  No socket associated with WebSocketHandler 0x0x7fbbec013080| ./net/WebSocketHandler.hpp:110

wsd-00027-00041 17:02:18.512048 [ docbroker_002 ] ERR  Cannot get file info from WOPI storage uri [https://[nextcloud FQDN]/apps/richdocuments/wopi/files/432_oc9778pwc3m8?access_token=zd4agTEcuTEhZhNEA8YCLqLCfAX3oMiP&access_token_ttl=0&permission=edit]. Error: Timeout: connect timed out: [nextcloud server IP]:443| wsd/Storage.cpp:532
wsd-00027-00041 17:02:18.512319 [ docbroker_002 ] ERR  Failed to add session to [[nextcloud FQDN]:443/apps/richdocuments/wopi/files/432_oc9778pwc3m8] with URI [https://[nextcloud FQDN]/apps/richdocuments/wopi/files/432_oc9778pwc3m8?access_token=zd4agTEcuTEhZhNEA8YCLqLCfAX3oMiP&access_token_ttl=0&permission=edit]: Timeout| wsd/DocumentBroker.cpp:847
wsd-00027-00041 17:02:18.512410 [ docbroker_002 ] ERR  Error while loading : Timeout| wsd/LOOLWSD.cpp:2239

I have replaced my Nextcloud FDQN and my Nextcloud/Collabora IP

Collabora is running in Docker with it’s own exclusive domain with a Letsencrypt certificate.

Server OS: Debian 9 stretch
Nextcloud: 12.0.3
Richdocuments: latest from app store


Nu suggestions here? If I need to provide more logs I will happily provide.