Unknown Error when attempting to open document in OnlyOffice

Hello everyone, I’m running both Nextcloud and OnlyOffice in docker containers behind Traefik. Nextcloud can successfully connect and healthcheck the OnlyOffice instance but it cannot open any files with it. Each time you attempt to open a file, it loads the OO page but then an “Unknown Error” popup occurs. I have tried other fixes like ‘overwriteprotocol’ => ‘https’, in the config.php but that does not seem to be helping. My Traefik is version 2.1, NC is 18, and I’m using the latest image of OnlyOffice document server. Each of the Traefik configs have passhostheader set to true at the moment. Has anyone else encountered this?

Found the solution here: