MSSQL 2017 was installed in Windows Server 2016. OpManager is now installing in the same server.

An SQL Server local account was created - named "opm". Confirm can login through SQL Management Studio.

At the stage of "Select the backend database for OpManager". Choose "SQL Authentication"

Host name is <the_computer_name>

Port is 1433

Database name is OpManagerDB

User name is opm

Password is <the_password_of_opm>

After click "Next". Shows "Host name or port number is incorrect".

Already tried input Host name as "<the_computer_name>\<instance_name>".  But this shows "Host name is invalid or not reachable"

Situation not change even turned off the firewall.