Can't get ReadyCloud to work

I have a RN3220 that I'm trying to setup ReadyCloud on and and not having any success... :(

When turned on I get a green tick for the Internet access but after a while the spinning icon next to that turns to a red cross with a services not available message.

I've read somewhere in one of the many threads I've looked at that this was caused by not having DNS set correctly. I've checked and the DNS settings are the same as all my PC's use so that doesn't appear to be an issue.

My firewall allows all traffic out and any return traffic back in but to be sure I've added a rule to allow port 6300 in to the NAS.

Still same result.

Can anyone suggest what else may be wrong or I may have missed please ???