Thanks for that sub-routine.
Using the http address as suggested I was able to connect to the router and discovered that for some strange reason the port forwarding was not active for port 443.
Once I had switched it back on, I was able to access the ISY using the https address and gain access to my admin console!!
Thanks to all the guys on the forum, another problem solved. Although I think I will still go down the DynDNS route when I get back over to Florida in a couple of months. (just for peace of mind)
Dave......