Microsoft Defender Firewall is one of the many security features available on Windows 11 to protect your computer and files from outside threats as well as from inside threats trying to get out.

A firewall works as a gatekeeper and blocks unused network ports, and every time an app wants to communicate outside your device, it checks if a rule exists in its database to allow or deny network access. If a rule doesn’t exist, the firewall will prompt you to identify and grant or deny permission.

While the Microsoft Defender Firewall does a pretty good job managing which apps and features should connect through the network automatically, sometimes you may need to allow or deny an app manually.

To allow an app through the Windows 11 firewall, use these steps:

1. 1. Open Windows Security.
   2. Click on Firewall & network protection.
2. Click the “Allow an app through firewall” option.
3. Click the Change settings button.
4. Check the app to allow through the Windows 11 firewall.
   Quick tip: If the app isn’t on the list, click the Allow another app button to locate the application you want to allow.
5. Check on which type of networks an app can access the network:
   • Private — Allows the app network access at home or work.
   • Public — Allows the app network access at a public place, such as in a coffee shop.
6. Click the OK button.

If you want to block an app through the firewall, you can follow the instructions outlined above, but on step No. 5, make sure to clear the checkmark for the app or feature you want to deny access to the network.

This guide focuses on the Microsoft Defender Firewall. However, if you have another security solution, the instructions will be different, as such, you should check your software company support website for more specific steps.