Win7 sets the firewall to prevent other hosts from accessing a port of the machine

First understand the inbound rules and outbound rules: inbound is when someone visits you, and outbound is when you visit someone else.
Open “Control Panel”->“System and Security>->“Windows Firewall". Click "“Advanced Settings" on the left panel; "Advanced Security Windows Firewall" window:

Click on the "Inbound Rules" on the left side and click on the "New Rule" on the right. ”, select “port”:

<;next” after selecting protocols and ports, such as TCP and 4000 ports:

“Next”after selecting“ Block the connection>:

Next, choose as needed:

Last, set the name, click “Complete”:

The firewall will enable the new rule by default. .