SQL Connectivity Issue From Cloud app to on-prem server

@Santhi Dhanuskodi we are sorry to hear you're facing these issues. You're right, the intermittent SQL connectivity issues with your .NET Core MVC app could be a problem with the Azure Relay Hybrid Connection.

Here's how you can troubleshoot and identify the root cause:

1. Azure Relay Hybrid Connection Logs:

• Event Viewer: On your on-premises server where the Hybrid Connection Manager is installed, open the Event Viewer. Navigate to "Applications and Services Logs" > "Microsoft" > "Service Bus" > "Client."
• These logs might provide insights into errors or warnings related to the Hybrid Connection establishment or communication with Azure Relay.

2. Azure Portal Logs:

• Go to the Azure portal and navigate to your Azure Relay resource.
• Under "Monitor," you'll find "Namespace logs" and "Connection logs."
• Namespace logs might reveal issues with the overall Azure Relay service health. Connection logs, if enabled, could offer details specific to your hybrid connection and communication attempts.

3. Network Connectivity Checks:

• Verify that there's no firewall rule blocking outbound connections to Azure Relay ports (TCP 443) on your on-premises server.
• Use tools like ping or tracert to confirm network connectivity between your on-premises server and the Azure Relay service endpoint.
• Consider temporary measures like disabling security software firewalls on the on-premises server to isolate if these are causing intermittent connectivity issues. (Re-enable them after testing)

4. Examine .NET Application Logs:

• Within your deployed .NET Core MVC app on Azure App Service, check the application logs for any exceptions or errors related to database connection attempts.
• These logs might provide more details about the specific SQL connection failure you're encountering (e.g., timeout, login issues).

5. Review Azure App Service Settings:

• Double-check your Azure App Service configuration for the connection string to your on-premises SQL server. Ensure it uses the correct hostname or IP address, port number, and credentials.

Hope that helps.

-Grace

We cannt see any logs from SQL server which are useful for this.

Because the client app can't connect/reach SQL Server of which it isn't aware, so what should it log?

You have to check the complete network connection, e.g. FireWall could block the connection.

We dont see logs as said in this section. 'Namespace Logs' or 'Connection logs' not present in azure portal

2. Azure Portal Logs:

• Go to the Azure portal and navigate to your Azure Relay resource.
• Under "Monitor," you'll find "Namespace logs" and "Connection logs."
• Namespace logs might reveal issues with the overall Azure Relay service health. Connection logs, if enabled, could offer details specific to your hybrid connection and communication attempts.