I have problem to connect to apple store

Using an 1Phone 8 Plus I had problems connecting to various apps and the internet, including the App Store. Other issues included unable to restore from backup, iTunes wouldn't identify my iPhone or iPad, and the phone wouldn't reset. Strangely I was able to connect to BBC News, but not BBC Sport! Many suggestions received from Apple support, all ineffective. This occurred after the update to version 14.5 and still happened with 14.6. The solution was to remove AVG Internet Security from my phone and temporarily install a free VPN, X-VPN. The problem of interoperability will continue until Apple, Microsoft, and everyone else get together and pre-release new versions for testing. It has taken 4 weeks to sort this out. I will be sending the same information to AVG.

I'm sorry to hear you are unable to connect to the App Store, please follow the steps here for help.

That’s good news! Does Apple discuss changes with other suppliers? Is there a reason why AVG Internet security worked before the upgrade to rev 14.5 but after upgrade it was not possible to connect reliably to WiFi, the internet or the App Store as described in my original message?

Apple does do beta testing of its new IOS and OS software.

I am a user like you, so I don't know if Apple communicates with suppliers or not. The AVG Developer hasn't updated the app to 14.5 standards.