I have deployed a web2py application on a server that is running on Apache web server.
All seems to be working fine, except for the fact that the web2py modules are not able to connect to an external website. 
in web2py admin page, i get the following errors :
1. Unable to check for upgrades
2. Unable to download because:
   
I am using web2py 1.9.9, CentOS 5
I am also behind an institute proxy. I am guessing that the issue has to do something with the proxy configurations.
Try testing the proxy theory by ssh -D tunneling to a server outside the proxy and seeing if that works for you.
Web2py unable to access internet [connection refused]