You are trying to connect to a home network (Lan) from another ISP connection. Of course you can connect to it while your in the home network but not while you are outside, I may have a solution for this. Try setting up a
Virtual Server rule on the DGL 4500. Once logged into the DGL 4500 user interface, navigate to
Advance >
Virtual Server I hope this works out for you.
It should look something like this, except with your settings.
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Chris