The official website of KDE Neon is not accessibleThe official KDE Neon website cannot download KDE Neon files normally in China. The download links have been blocked and normal downloads are no longer possible.
KDE neon download page seems to be redesigned and files are no more downloaded from kde main site but from your nearest mirror site. In your case it seems to be mirrors.bfsu.edu.cn, and it seems to be accessible OK, at least from here (Estonia). As you seem to try the download with your mobile phone, maybe your mobile service provider is the cause of problem?