iOS 12 App Store login issue: "Could Not Sign In

Restart your equipment and/or sign in out and back in again, and try again.

If you can't connect or sign in to iCloud or your account, Apple has a list of things you can try in the support article: If you can't connect or sign in to iCloud - Apple Support

Is the appropriate Apple server working? --> https://www.apple.com/support/systemstatus

If your device is managed by a school or organization you may need to sign in to the device with a school or work Apple Account. More in this article —> If you can't sign in to your device with your personal Apple Account - Apple Support

If you are using a VPN try removing it completely (don't just turn it off) and see if you can then use the service. E.g., AppStore - Apple Community

If using cellular data (even if it is seemingly good), try using WiFi instead. —> Connect to Wi-Fi on your iPhone or iPad - Apple Support

If you are trying to use a service from outside your Home Country it may not be available. From: Apple Media Services Terms and Conditions - Legal - Apple Media Services - Apple

- A. ”Our Services are available for your use in your country of residence (“Home Country”).

And: "Certain Services and Content available to you in your Home Country may not be available to you when traveling outside of your Home Country."

For more assistance try the iCloud Support web site --> iCloud - Official Apple Support

If you still have problems try official Apple Support. Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

am using ios12 on my iPad am having problem to download apps on iTunes Store