Can't Connect to Apple Store

New Contributor II

Hi all,

We having issue connecting to Apple Store even the Apple server block addresses are opened.
Apple Store and iCloud are enabled (Restrictions>>Preferences: Enable selected items) via Jamf Pro.
I've created a static group and an enabled-AppStore-iCloud profiles for certain Macs that approved by security/network team.

Error messages for Sierra (10.12.6): - Verification Failed - You can't sign in at this time

Error messages for Mojave (10.14.1): I could sign in, but can't connect to the App Store server; a blank page

Need you guys suggestions.