Need help getting nextcloud talking with standalone onlyoffice server

So I have both nextcloud and a standalone onlyoffice server both up and running. They both are running SSL via letsencrypt, working great.

I’ve enabled the ONLYOFFICE app and I then pasted in the URL of the onlyoffice server (https://onlyoffice.domain.ca). However when I click “Save” I get an error “Error when trying to connect (Bad healthcheck status)”.

I see the log entry below. Thanks!

|Error|onlyoffice|Exception: Bad healthcheck status

  1. /var/www/html/apps/onlyoffice/controller/settingscontroller.php - line 170:OCA\Onlyoffice\DocumentService->checkDocServiceUrl()
  2. /var/www/html/lib/private/AppFramework/Http/Dispatcher.php - line 169:OCA\Onlyoffice\Controller\SettingsController->SaveAddress()
  3. /var/www/html/lib/private/AppFramework/Http/Dispatcher.php - line 100:OC\AppFramework\Http\Dispatcher->executeController()
  4. /var/www/html/lib/private/AppFramework/App.php - line 152:OC\AppFramework\Http\Dispatcher->dispatch()
  5. /var/www/html/lib/private/Route/Router.php - line 308:OC\AppFramework\App::main()
  6. /var/www/html/lib/base.php - line 1009:OC\Route\Router->match()
  7. /var/www/html/index.php - line 37:OC::handleRequest()|
    | — | — |

I am still trying to figure this out and would appreciate any comments. I just updated NextCloud from 20.0.1 to 20.0.9. Not updating to 21 yet as that broke all of my external storages last time. Both servers are running fully up-to-date Debian 10.8. Still getting the exact same error message as before.