Messages and Network Connection error

[greekharry]

Hi Folks,

I've had this problem since Mavericks but with a far less descriptive error...

Anyhow, when I try to sign into iMessage using my AppleID, I get the following error message:

Could not sign in. Please check your network connection and try again

So, my network connection is working, ergo this post, but what network connection is the Messages application looking for and how can I fix this?

Thanks in advance for any assistance!

Cheers,
Harry