Sql-server – How to allow remote connection in SQL Server 2008 Express

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.

Ensure that the secondary instance (in this case SQL Express) has a TCP port set.

1. Under SQL Server Configuration Manager, go to SQL Server Network Configuration, then Protocols for [INSTANCENAME].
2. Right click TCP/IP and under the IP Addresses tab make sure the field "TCP Port" has a value (for example 1533).

Then try to connect to the instance with the newly assigned port:

172.16.11.2\sqlexpress,1533

Voila!