testflight cannot access the App Store

I connected the 5G network with the following method, but even the non-5G wifi is useless.

Open the settings—click into the wireless LAN—click the small exclamation mark on the right side of the Wi-Fi you are connected to—click Configure DNS—change to manual, add a server: 8.8.4.4
as shown below:

Use of iOS-TestFlight

Reference blog:
Why can't testflight access the App Store?
Testflight can't connect? Four solutions for Testflight unable to connect to AppStore Connect