I use win11. I also prompt ：
HTTP host https://maven.google.com/ is not reachable. Reason: An error occurred while checking the HTTP host

but I can open this URL.

E:\flutter>flutter doctor
Flutter assets will be downloaded from https://storage.flutter-io.cn. Make sure you trust this source!
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 2.10.0, on Microsoft Windows [Version 10.0.22000.318], locale zh-CN)
[√] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Community 2019 16.11.7)
[√] Android Studio (version 2021.1)
[√] IntelliJ IDEA Community Edition (version 2021.2)
[√] VS Code, 64-bit edition (version 1.63.2)
[√] Connected device (3 available)
[!] HTTP Host Availability
X HTTP host https://maven.google.com/ is not reachable. Reason: An error occurred while checking the HTTP host: