Nextcloud/Onlyoffice "DS is Running, won't open documents"

Installed NGINX, Nextcloud, by following: and onlyoffice/docker instructions from: Nextcloud and ONLYOFFICE (NGINX) – Carsten Rieger IT-Services, and followed the steps at the bottom to install as a subdomain in a docker.

Nextcloud seems to be working just fine. cloud.mydomain.tld (no issues and settings—>overview/logs are clear)
Onlyoffice seems to be working - onlyoffice.mydomain.tld (Document Server Is Running) message displayed when you go to https://onlyoffice.mydomain.tld

When I attempt to open a .docx file:
This content cannot be displayed in a frame:
To help protect the security of information you enter into this website, the publisher of this content does not allow it to be displayed in a frame.

In Chrome: (Sad Page Icon) with the words: onlyoffice.mydomain.tld refused to connect.

Checked /var/log for errors related to onlyoffice - nothing of note
Checked the /var/log in the docker, and all of those are empty.

I’m not sure where to go at this point. I’ve tried adding the trusted_peers to the config.php in nextcloud, no help.

Please help! I’m just not even sure where to look to find the problem.

Did you find a solution for this? Having a similar problem…