PC Terraria Will not Launch, through Steam or Otherwise

[punchready]

Not unless you live in a dangerous neighborhood.

Which the internet often is. Hense why I advised them to not turn it off completely.

Anything that wants to connect to a computer in your (typical) home network from the internet *must* go through your router, which (by default) will not allow that at all, on any port.
This is also why for example the Terraria server will ask you if you want it to "automatically forward port": if you agree, it will ask your router to allow outside connections through port 7777 (or whichever port you selected)