How can I connect to my SQL server from my VM using a .NET application.

Hello,

Based on the thread, here are some additional solutions that haven't been mentioned yet:

Network and Environment Checks:

• Verify your VM's outbound internet connectivity isn't blocked by NSG rules
• Check if there are any proxy settings or corporate firewalls on the VM that might interfere with Azure SQL connections
• Ensure the VM can reach *.database.windows.net on port 1433

Authentication Context Issues:

Since you can connect via SSMS but not your console app, this suggests the VM has different user context than your local machines. Try these approaches:

1. Run the console app as the same user account that successfully uses SSMS
2. Test different authentication methods in your connection string: In your .NET console application, modify your connection string to try these authentication methods one at a time:

   Authentication="Active Directory Interactive";
   Authentication="Active Directory Password"; 
   Authentication="Active Directory Service Principal";

Replace the Authentication="Active Directory Default"; part in your current connection string with each of these options and test.

VM-Specific Troubleshooting:

• Install the latest Microsoft.Data.SqlClient NuGet package on the VM
• Ensure the VM has the proper .NET 8 runtime and all dependencies
• Check if there are any antivirus or security software blocking the connection
• Verify the VM's system time is synchronized (authentication tokens are time-sensitive)

Debugging Steps:

• Add detailed logging to your console app to see exactly where the connection fails
• Test with a simple connection string first, then gradually add complexity
• Use SqlConnection.ConnectionTimeout to determine if it's a timeout vs authentication issue

Alternative Authentication:

• Consider using Managed Identity if your VM supports it
• Try certificate-based authentication
• Use a service principal with client secret authentication

The key insight is that "Active Directory Default" authentication relies on the current user context, which differs between your local machines and the VM environment.

Hope this helps solve your connection issue! Let me know if you need any clarification on these approaches.