Sql-server – Cannot connect to SQL Server from Management Studio (both 2012)

This sounds like a network problem; if the other remote clients can access the instance then it seems unlikely it is an instance-specific problem.

1. Be sure that firewalls on the notebooks are turned off or (better) are allowing TCP traffic through the port your server is using.

2. If you are connecting using the server's host name or machine name, make sure it resolves to the correct IP from the notebooks. Try this from a command prompt on the notebooks:

   C:\> ping my.databaseserver.com
   

   or

   C:\> ping OUR_SQLSERVER 
   

   In the output the IP address to which my.databaseserver.com/OUR_SQLSERVER resolves will be displayed.

3. See if you can connect directly via TCP to check for misconfiguration of the SQL clients. On the notebooks, type this at a command prompt:

   C:\> telnet 192.168.1.200 1433
   

Substitute your SQL Server's IP and the port it is using. The reply you get will not be readable, but unless you get a message like Could not open connection to the host, on port 1433: Connect failed, you are at least able to connect to the server.

Hope this points you toward a resolution.

You should not need to specify the port for a named instance (that's kind of the point of the name - and since it's dynamic you won't want to hard-code a port into your connection strings etc. unless you want to change your config files every time the port changes). Try connecting to:

123.123.123.123\SQLEXPRESS

Also make sure that your server is exposed to the Internet on that port (firewalls may be preventing this) and that the SQL Browser service is running.

PS Ping means nothing. You need to try to telnet to the port that SQL Server is exposed on.