Hello there !
With a fresh installation of Jenkins, I run into this problem when I try to install a plugin.
Is it linked to the fact that my server has ip v6?
Looking forward to hearing from you ^^
Mysterious_Dev
The updates.jenkins.io machine is not yet accessible from pure IPv6 networks. A Jenkins infrastructure help desk ticket is tracking the issue.
I believe that you’ll need to find a way to allow that IPv6 machine to access the IPv4 address of updates.jenkins.io