What kind of proxy?

https or http proxy ?

Have you looked in the proxy logs to see if your appserver is being allowed through?

Can the proxy connect to the redhat site ?

so when you said "We were able to download the patches without any Proxy" and show errors that mention a proxy server that seems to imply that if you bypass the proxy the download works but when you use the proxy you get the noted errors.

so how are you able to download patches w/o issue?  is that using the same path to the internet that the appserver does when you see these errors ?

I cant reach the URL in that error message either - looks like Red Hat has a problem