Troubleshooting Intermittent Connection Failures

Intermittent connection failures are usually caused by environment/setup issues and require some environment troubleshooting to determine the cause. The following are some good resources that users have used to troubleshoot these kind of issues:

Troubleshooting SQL Client / Server Connectivity Issues
0400 Consistent Authentication Issue
0420 Reasons for Consistent Auth Issues

For Azure DB we also recommend increasing the loginTimeout property value to 90 or 120 as higher timeouts are necessary due to network latency. In addition, starting with version 9.4.0 there are also open connection retry options that might help as well as it will retry failed connections. Please see Setting the connection properties for more info on how to set connection properties for the driver.

Finally, one could also enable traces from the driver to see if it gives any hints to what was happening at the point of failure. Please see Tracing driver traces for more info on how to enable driver traces.