|Thanks to all of you for trying to help!|
"This suggests his DSL modem is also a router, or he is somehow otherwise behind a router. If his computer has a private IP address, something (port forwarding) must be done to bridge the connection between his public IP and private IP."
His PC connects to just one device (It's not like PC - Router - Modem), so the device is a modem cum router as you rightly pointed out. The make is Shiro.
How to configure port forwarding?
"have him go to shields up! and test for port 3398 to see if it is open or not."
You mean 3389 right? It is open as the option "Allow users to connect remotely to this computer." is checked in the properties. And just to confirm, he had it checked with Shields Up as well - it's open.
"And which IP are you trying to access? Do you receive any errors?"
I'm trying yo access his public IP address, obviously not the private. This is the error I get: "This computer can't connect to the remote computer."
"Could just go to Acrobat.com and use it. Seems to work on hardened systems."
Didn't get that - mind elaborating?