I had this a while ago and asked David. It is something to do with the connection that you have at your end - when the internet connection you are using is limited, you get this message. I got it when trying to access remotely on my phone in an area of limited bandwidth - at home it was fine.

Disclaimer - I know very little about computers other than the programmes I need to use, and so David may tell you I am talking rubbish but that was the rough explanation when I had the same problem once!

Jason