2. Ensure that the SQL service port of the server is available.
Use the telnet ip port number at the windows command prompt.
The port is available normally and a blinking cursor will be displayed.
The port is not open, as shown below. Possible reasons are: 1, SQL service started; 2. Firewall blocked port 3. Port error 4. Network failure.
3. As shown in the figure, the server turned off remote access.