Chef-server-ctl reconfigure Errno::ENETUNREACH

I run opensource chef server at AWS VPC. Chef 12.5.0, Ubuntu 14.05
When I run chef-server-ctl reconfigure I got error:
FATAL: Errno::ENETUNREACH: apt_repository[chef-stable] (private-chef::add_ons_repository line 15) had an error: Errno::ENETUNREACH: remote_file[/opt/opscode/embedded/cookbooks/cache/gpg.key] (/opt/opscode/embedded/cookbooks/cache/cookbooks/apt/providers/repository.rb line 59) had an error: Errno::ENETUNREACH: Network is unreachable - connect(2) for “packagecloud.io” port 443

Instance uses proxy which is configured. curl and wget are able to connect internet. I did test:
wget https://packagecloud.io/ and I got reply.
As next step, I temporarily assigned elastic IP to instance. but it did not help.
Any sugestion?

Zdenko

You need to upgrade to a version of Chef Server newer than 12.6, but preferably the latest release.