User Profile

Today i found that my enterprise apps with valid distribution certificates and provisioning profiles not work at all. In General -> Profiles & Device Management its not verified. When i'm trying to verify apps i'm catching the warning with the following: "Unable to Verify iPhone Distribution: My Distribution certificate" Apps. A network connection is required to verify "iPhone Distribution: My Distribution certificate" apps on this iPad. Connect to the Internet and try again". But everything is OK with my internet connection. I found even here: https://support.apple.com/en-gb/HT204460 that there is a service ppq.apple.com, that verifies enterprise apps, but this service is unavailable on link: https://ppq.apple.com , return error 503. Whats happened and how can i fix this issue? And how periodically does the Apple device checks the verification status of the distribution certificates of my app? Am i alone face this issue?