Hi,
I got the error at Extension Management page.
The plugin repository could not be contacted. Make sure your server is allowed to contact www.dokuwiki.org and check your proxy settings. [Retry]
I search the forum find some post, (https://forum.dokuwiki.org/d/20344-the-plugin-repository-could-not-be-contacted but had no clue.
I tried to use wget command, looks fine.

My network set is below, I tried to check and uncheck the two options, but nothing changed.

Any suggesion where shall I trouble-shooting for it?