I see a blank screen and no connections

Due to some privacy changes in Android 10+, the regular apps no longer have access to the core kernel files. With Android 10+ you need to ROOT your device in order to use the app. More information here: https://www.xda-developers.com/root/

Can it track connections using a vpn?

Yes, you can use a VPN and still track the connections to the real IPs.

some connections are not captured?

Uncheck "Android System" checkbox in Settings. This will force the app to show all connections (even those that still don't have assigned process ID to it).

Can I track IPv6 connections?

Yes, the app supports IPv6 addresses for both local and wide area networks.

Is there a version for iOS?

No, we don't provide an iOS version of the app and we don't have plans to make one.

if I purchase an unlock key on a device, would my other Android devices with the same Google account will work as well ?

Yes, the license key is tied to your Google account, so it will work on all devices where you put your Google account.

I bought the unlock key, but it does not appear as program shortcut to access it?

The Unlock key doesn't have a launcher icon. It just activates the Network Connections app. Please note that the unlock key will not work if you copy it between devices, or restore it from backup. You should install it directly on Google Play Store.