I've install SQL Server Express 2014 named instance with mixed mode authentication.
one more SQL Server 2005 version installed with default instance and TCP port has been assigned 1433.
following error occurred
Server Name: .\sqlexpress
Error Number: 18456
Line Number: 65536
-I want to connect locally (with dot) but not able to connect, I also want to connect from outside network
-with static IP still getting the same problem.
following changes I've done
-remove dynamic TCP port from configuration manager ipall
-instead of dynamic port I've place static tcp port 1438 and 1440 both are listening
-try 1434 TCP port but SQL service not able start so I've change into 1438 and 1440.
-and same has been configured from firewall inbound and outbound rule.
--also tried through dbeaver to make connection but following error occurred
SQLEXPRESS,1438 failed. Error: "java.net.UnknownHostException: 18.104.22.168:3390: invalid IPv6 address". Verify the server and instance names and check that no firewall is blocking UDP traffic to port 1434. For SQL Server 2005 or later, verify that the SQL Server Browser Service is running on the host.