Onlyoffice Bad Gateway 502

I did the installation of Nextcloud, after Onlyoffice by Nextcloud and document server too and then I installed the Document server following the wiki:
But now I get this error: 502 Bad Gateway and I have read many documents and posts to resolve and nothing the error continues.

NethServer release 7.7.1908 (final)
Nextcloud 18.0.3

It’s not clear, you have 502 error when you attempt to connect to your NextCloud ?

I have this error when configuring Onlyoffice on Nextcloud and also when I try to access Onlyoffice directly in the browser

Check this link of the official doc (at the end) :

There is something weird about document server on nethserver. According to the official documentation, nethserver doesnt support OO document server : “Installation of full ONLYOFFICE server is not supported on NethServer.”.
I don’t know very well nethserver, so maybe i’m wrong.

You can install onlyoffice with the document server app on the NextCloud web interface.

How did you try to install OnlyOffice? Are you using a docker version?

I use the normal version, installed by Nextcloud even in the Applications option