Freshly installed Jenkins returns an error "Unable to connect to Jenkins" after chosing "Install suggested plugins" during initial setup through wizard.
The server is able to reach https://updates.jenkins.io/current/update-center.json and http://updates.jenkins-ci.org/update-center.json (the former configured by default)

Also I've tried latest weekly build and jenkins:jenkins docker container an always got the same behaviour

Upd: Stacktrace (/var/log/jenkins/jenkins.log) can be found here: https://pastebin.com/nJ9XzbJY

Upd2: `--httpKeepAliveTimeout=60000` "removes" the exception, but wizard still isn't working and returns an error as indicated above

It's a duplicate of https://issues.jenkins.io/browse/JENKINS-46776 but I've decided to create a new issue to attract attention.

In my case RTT of request was about 1.76min (firefox stats). I understand that such problem caused because of slow VPN and ugly server, but that blocks installation process without any explaniations