SQL server clustering the timeout period elapsed prior to completion of the operation

Recently I faced one of our application could not connect. It throws an error ” Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding. (Microsoft SQL Server, Error: -2) ” I found the problem. It’s because of firewall.

SQL Cluster error:

Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. (Microsoft SQL Server, Error: -2)

We are using SQL server failover clustering on our application, after a failover occurred the application could not connect it. It’s used a default instance, default port and the connection string are correct (FQDN) even though it’s not connected because the firewall prevents the SQL server (port). Again I failed over the server it works fine. It’s a simple problem. Therefore the problem is the Installation team created inbound rule on one server not the other passive server.

Run –> Administrative tools –> Firewall –> Inbound rule–> Right click –> New rule –> Select port –> Click next –> Enter the SQL server port number –> Select the default –> Next –> Select the profile whatever you want –> Enter the name

The conclusion is always creating a firewall rule to all the nodes after finish a SQL clustering installation.