The nextcloud app does not support IPv6

Two servers are built by ourselves. The nextcloud domain name is www.xxxx.cn and the emby domain name is tv.xxxx.cn. These two domain names only provide IPv6 addresses without IPv4 addresses.

The version of nextcloud app is nexcloud dev android app, version 20211202. When WiFi connection is used, nextcloud app only uses IPv4 parsing, not IPv6 parsing. It is provided as “server not available”, while emby app can be used normally and parsed with IPv6.
屏幕截图 2021-12-04 100502

Till now I had the feeling the app (maybe Android itself) prefers IPv6 … Little surprised about your post but it sounds you are confident… for me it’s a clear bug - I think it’s better you file a bug report on Github

Thank you.