MSSQL: Enabling and Disabling SQL Server Remote Connection

If a user is having issues connecting to the SQL Server remotely. This may worth a look. By default, it is set to "1" or ON and allowed connecting from a remote client. Another common type of connectivity issue might be connecting to Named instance or non-default port which discussed in another blog. 

To turn it OFF.

 EXEC sp_configure 'remote access', 0 ;   
 GO   
 RECONFIGURE ;   
 GO   

Remote connection troubleshooting reference