When connecting to an Azure IaaS SQL Server Cluster (and Availability Group) that was configured to use an Azure Internal Load Balancer, more on this in another post, I received the following error.

“Failed to connect to SQL Server XXXX (Microsoft.SQLServer.ConnectionInfo)”

“A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 – Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 53) ”

“The network path was not found”

This was found to be down to NetBIOS being enabled for the SQL Server IP Address

Changing the cluster resource settings

Enable NetBIOS for this address from checked to unchecked resolved the issue

This can also be achieved using PowerShell

“SQL IP Address 1 (############)”

-Name “EnableNetBios”

This is detailed in the post Configure one or more Always On Availability Group Listeners – Resource Manager under
Configure the IP resource for the availability group

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