Exception: Bad healthcheck status Onlyoffice internal

Nextcloud version _19
Operating system and version Ubuntu 18.04LTS
PHP version: 7.4.7

I’d really like to see ONLYOFFICE run on my webserver. All this server runs is Nextcloud.

It is behind a NAT and with a SSL, but I’m pretty sure it all works correctly. DNS and Certificate are working.

I can use the ONLYOFFICE demo server fine, but when I point to me, I get:
Exception: Bad healthcheck status
/var/www/clients/client1/web1/web/share/apps/onlyoffice/controller/settingscontroller.php -
line 171:

OCA\Onlyoffice\Controller\SettingsController->checkDocServiceUrl()

/var/www/clients/client1/web1/web/share/lib/private/AppFramework/Http/Dispatcher.php - 
line 170:

OCA\Onlyoffice\Controller\SettingsController->SaveAddress()

/var/www/clients/client1/web1/web/share/lib/private/AppFramework/Http/Dispatcher.php - 
line 100:

OC\AppFramework\Http\Dispatcher->executeController()

/var/www/clients/client1/web1/web/share/lib/private/AppFramework/App.php - line 137:

OC\AppFramework\Http\Dispatcher->dispatch() /var/www/clients/client1/web1/web/share/lib/private/AppFramework/Routing/RouteActionHandler.php - line 47:

OC\AppFramework\App::main()

<<closure>>

OC\AppFramework\Routing\RouteActionHandler->__invoke()

/var/www/clients/client1/web1/web/share/lib/private/Route/Router.php - line 297:

call_user_func()

/var/www/clients/client1/web1/web/share/lib/base.php - line 1007:

OC\Route\Router->match()

/var/www/clients/client1/web1/web/share/index.php - line 37:

OC::handleRequest()

BTW, had to install the Community Document Server from the CLI, but it’s in and then I uninstalled ONLYOFFICE and re-installed it.

THX in ADV!

Bad healthcheck is usually SSL related in my experience.
How is OO SSL’d?

Using Let’s Encrypt. I can verify SSL from outside and inside. How about the port that Onlyoffice uses? I am behind NAT.

The error occurs when I try to apply the Document server URL + using advanced settings as well to specify internal URL (which is the same as from outside!)

What do the Onlyoffice posts mean encouraging me to install an external Onlyoffice Document Server? I can’t even find instructions on how to install Onlyoffice Document Server? I thought the document server was provided by the Community Document Server (which I installed from the CLI)?

Since you can use the OO demo server without issues, the NC part is OK…

You can either install the OO app into NC (about 200MB) or use/install an external OO server.
I have not done the former. But a standalone OO server needs to be properly SSL’d to work.
If not, it’ll throw a Bad healthcheck error…

And it is always a good idea to uninstall/reinstall the OO connector app after doing some changes to the OO server - app or standalone…

So that brings to mind: how do I install OO Server? Is that the same thing I installed with:

php cc app:install documentserver_community

SOLVED: Needed OO Server installed as Docker to not conflict with Apache:
wget http://download.onlyoffice.com/install/opensource-install.sh
bash opensource-install.sh
Answer Y to the install Docker prompt
THX