Windows Security can alert you if the firewall is blocking an app, but there are other signs to look for if it doesn't. You ...

PureVPN confirmed that it is working to patch these issues by mid-October, while ensuring that no other apps are vulnerable.

Linux is highly secure, but you should still have a firewall. You should know if your ISP's hardware (gateway) uses a firewall. One of the easiest Linux firewalls is UFW and its GUI sidekick, GUFW.