NC can't connect to Onlyoffice

I’m using NC 15.0.4 in a LXC on Proxmox and have on a different LXC the onlyoffice installed (NOT with this piece of crap called “docker”). If I type in the IP of this LXC, I get “document server running”. I added this to my reverse proxy with a new subdomain and if I enter this I get “document server running”, too. But if I enter my subdomain (with ssl!) into the onlyoffice configuration in NC I get this errors:
“Error onlyoffice HealthcheckRequest on check error: Bad Request or Timeout Error”
“Error PHP file_get_contents( failed to open stream: Connection timed out at /var/www/nextcloud/apps/onlyoffice /lib/documentservice.php#385”
“Error PHP implode(): Invalid arguments passed at /var/www/nextcloud/apps/onlyoffice/templates/settings.php#66”

I also added
‘onlyoffice’ =>
array (
‘verify_peer_off’ => TRUE

at the end of my config.php, but nothing. What’s wrong?

I’m using docker and i have installed it on a different server , everything works but the connect via DocumentServer, exactly the same errors pops at me too. (identical) Maybe it’s something from their side …? #Bugs? Because i cannot find anything useful to fix this…

Hope someone can provide some help ~.