Intermittent SQL Server Connectivity Issues: How to Diagnose and Resolve?

Question

I'm experiencing intermittent connectivity issues with our SQL Server, and I'm looking for advice on how to diagnose and resolve them. Here are the details:

1. Error Messages:
   • [HYT00][Microsoft][ODBC Driver 17 for SQL Server]Login timeout expired
     • [08001][Microsoft][ODBC Driver 17 for SQL Server]TCP Provider: Error code 0x102
       • [08001][Microsoft][ODBC Driver 17 for SQL Server]A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online.
       1. Issue Characteristics:
          • The connectivity issue occurs sporadically, without a consistent pattern.
            • Sometimes connections work perfectly fine, other times they fail with the errors mentioned above.
              • The problem affects multiple clients connecting to the server.
              1. Environment:
                 • SQL Server Version: SQL Server 2019.
                   • ODBC Driver: ODBC Driver 17 for SQL Server.
                     • Network: Clients are on the same local network as the server.
                       • Firewall: Ports are configured to allow SQL Server traffic.
                         • Server Load: No apparent load issues when checked during problem periods.
                         1. Troubleshooting Steps Taken:
                            • Network Checks: No significant packet loss or latency spikes detected with ping and traceroute.
                              • SQL Server Logs: No unusual errors or signs of resource contention.
                                • Timeout Adjustments: Increased connection timeout settings.
                                  • DNS: Flushed DNS cache, tried using static IP addresses.
                                    • Firewall: Verified that necessary ports are open and no dynamic rules should block traffic.

Can Please Someone help me on this:

1. What additional diagnostic steps should I take to identify the root cause of these intermittent connectivity issues?
2. Could specific SQL Server configurations contribute to sporadic connectivity problems, and if so, which settings should I review?
3. **Are there any known issues with ODBC Driver 17 for SQL Server that might cause such problems, and would updating the driver potentially help?**I'm experiencing intermittent connectivity issues with our SQL Server, and I'm looking for advice on how to diagnose and resolve them. Here are the details:
   1. Error Messages:
      • [HYT00][Microsoft][ODBC Driver 17 for SQL Server]Login timeout expired
      • [08001][Microsoft][ODBC Driver 17 for SQL Server]TCP Provider: Error code 0x102
      • [08001][Microsoft][ODBC Driver 17 for SQL Server]A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online.
   2. Issue Characteristics:
      • The connectivity issue occurs sporadically, without a consistent pattern.
      • Sometimes connections work perfectly fine, other times they fail with the errors mentioned above.
      • The problem affects multiple clients connecting to the server.
   3. Environment:
      • SQL Server Version: SQL Server 2019.
      • ODBC Driver: ODBC Driver 17 for SQL Server.
      • Network: Clients are on the same local network as the server.
      • Firewall: Ports are configured to allow SQL Server traffic.
      • Server Load: No apparent load issues when checked during problem periods.
   4. Troubleshooting Steps Taken:
      • Network Checks: No significant packet loss or latency spikes detected with ping and traceroute.
      • SQL Server Logs: No unusual errors or signs of resource contention.
      • Timeout Adjustments: Increased connection timeout settings.
      • DNS: Flushed DNS cache, tried using static IP addresses.
      • Firewall: Verified that necessary ports are open and no dynamic rules should block traffic.
   Can Please Someone help me on this:
   1. What additional diagnostic steps should I take to identify the root cause of these intermittent connectivity issues?
   2. Could specific SQL Server configurations contribute to sporadic connectivity problems, and if so, which settings should I review?
   3. Are there any known issues with ODBC Driver 17 for SQL Server that might cause such problems, and would updating the driver potentially help?

Answer 1

Hi @Vinith,

Thank you for reaching out and welcome to Microsoft Q&A.

The error message means the client cannot connect to SQL Server over the network.

Could specific SQL Server configurations contribute to sporadic connectivity problems, and if so, which settings should I review?

Here is a known issue like yours and this article is the official document, you can follow steps to troubleshoot your issue.

Are there any known issues with ODBC Driver 17 for SQL Server that might cause such problems, and would updating the driver potentially help?

I've checked the list of bugs fixed in ODBC. I don't find the same issue. However, keep the latest update is always good to avoid some unnecessary issues.

In addition, you can also try to use the Product Key in the SQL Server 2019 installation center Maintenance - Version Upgrade. There was a customer had the same issue before and he resolve it by this method, maybe you can try this.

Please feel free to share your issue here if you have any confusions.

Best regards,

Lucy Chen

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Answer 2

Could you resolve?