I understand that its a "proxy" problem (because its
working fine without
any proxy connection network). But not able to figure it out.
I set env variable http_proxy, https_proxy, ftp_proxy, no_proxy.
I also defined yum http_proxy, https_proxy, ftp_proxy and wgetrc http_proxy,
https_proxy, ftp_proxy.
If you need proxy only for yum, you can set it in yum configuration
(see man yum.conf) and leave env vars clean.
Cheers,
Alan