Please also make sure your servers are not behind a firewall. If they are you would need to configure the Proxy configuration - 

 

Open Apache Felix Web Console and configuration tab: http://localhost:4502/system/console/configMgr

and find a "Day Commons HTTP Client". Configure proxy server here.

For more details please check following link:

http://dev.day.com/docs/en/cq/current/deploying/configuring_osgi.html