Follow the below steps to open firewall from a specific IP address
1. Open Sql Server Configuration Manager 2. Open Sql Server Network Configuration 3. Double click Protocols for MSSqlServer (Instance Name) 4. Double click TCP/IP (Properties) 5. Go to IP Address tab and enter the specific IP address you wanted to allow connections (leave the default port to be 1433)
Restart the Sql Server when done with above steps.
Is this a named instance? , in that case, check the instance port number, it would not be 1433, may be dynamic too. Once you found out the port, you can check the connection this way too (126.96.36.199,portnumber) from SSMS. If this is not working, check the port blocking from server or firewall level. You can check if the connections are established or not through 'net stats' command.