I like to believe that I'm relatively smart, but this has daunted me for days now. Thump me and point me to the thread that I've missed, if you'll be so kind.

We have a very basic Airport network set up in our LA office (AT&T DSL modem bridged to an Airport Extreme with 2 Macs connected via ethernet and 2 Macs connected wirelessly; no funny business, no PCs, no third-party whatzits).

I need to be able to access the network over the Internet from our Minneapolis office, but when I use the afp://etc.etc.etc. obtained from Sharing on one of the network machines, the connection times out. Is this due to it being behind the Airport (same effect whether the Mac is wired or wireless), due to the dynamic IP addresses, or due to a checkbox that I missed on a control panel?

Any and all solutions graciously appreciated!