Error thrown while trying to upload cookbook to hosted chef server

I want to upload a cookbook to hosted server.

Command Run : knife cookbook upload CookbookName

Error Received :
Uploading CookbookName [0.1.0]
Failed to open TCP connection to s3-external-1.amazonaws.com:443 (A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. - connect(2) for “s3-external-1.amazonaws.com” port 443)
Check your knife configuration and network settings

I could not find any leads on this. Any help is appreciated.