Nextcloud v28 - OnlyOffice Install Error

I am running the latest Nextcloud version 28.05.5 which I installed using a GitHub auto install script. It is directly installed onto my fileserver running on the latest Ubuntu Server OS. In other words, it is not installed using Snap or Docker. Recently I installed OnlyOffice by goiing to the APPS page and installing the “Community Document Server” and “ONLYOFFICE” Nextcloud modules. Below is the error I get when I attempt to SAVE the configuration:

Error when trying to connect (cURL error 60: SSL: no alternative certificate subject name matches target host name '123.456.7.899' (see for https://123.456.7.899/apps/documentserver_community/healthcheck)

Has anybody out there encountered this problem? My Nextcloud installation script auto generated Self Signed Certificates for HTTPS operation. So I am not clear why OpenOffice does not just adopt the already existing Nextcloud Self Signed Certificates being that the OnlyOffice app is already operating within a NextCloud environment.

Nevertheless, the “Community Document Server” GitHub page mentions if Nextcloud is using a self signed certificate for https it is necessary to import the certificate into Nextcloud’s certificate store to make the “Community Document Server” work. They say to use the SUDO command below:

sudo -u www-data php occ security:certificates:import /path/to/certificate

What is the correct way to execute the “OCC” command above? I ask because when I attempted to execute the command below which lists your installed certificates:

sudo -u www-data php occ security:certificates

I got the error below in my Ubuntu Server terminal:

Could not open input file: occ

I would appreciate any opinion confirming if the OnlyOffice SSL Error I am getting can be fixed with the SUDO command that imports SSL certificates. Is this the correct solution path to pursue? Thank you for your time.