SQL 2019

Thanks for the reply.

There could be a couple of possible causes for that.

1. SQL Server application is currently stopped/not running on the server
   
   to resolve this, make sure that the "Microsoft SQL Server (MYOBACCT)" is running in the Windows services control panel.
   
   
2. Firewall is preventing access to SQL server from workstations
   
   It's possible that firewall rules don't exist in your firewall to allow SQL "clients" to connect to the SQL server.  This is a bit trickier to resolve.  Troubleshooting your Firewall product is not really covered by MYOB support as it's environmental. 

If the Firewall is the cause, then it would require rules to be created in your firewall to allow SQL clients (such as the MYOB application) to be able to "talk" through the firewall rather than being blocked.

SQL server uses a range of ports, including TCP/UDP ports 1433 and 1434, as well as a "range" of ports used for dynamic ports - this is set inside the SQL application at install, based on your system.

In order the set the appropriate ports, you'd need to confirm what ports of being used by the SQL server using the SQL Configuration Manager tool - this can be a bit tricky.

If you are using Windows Defender as your firewall (This is the default firewall product in Windows) , then please reach out to support team.  I've advised them of this post.