Having just got my cisco 877VA router up and running I have now noticed that a day or two later when being away from home everything locally seems to work fine but I have a network aquarium controller for my tank that I can log on to remotely to check the parameters and alter several devices on my aquarium, I can't seem to see my aquarium controller externally i.e. from the internet I can usually check this on my ipad when I work away but I don't seem to see it now although it's still there locally.
I have checked all I.P. addresses and I've checked that I can see port 80 and can ping cannonz.dyndns.org which I can, it previously worked before I upgraded to my new cisco router.
Could someone please help me as what could be wrong.