Maybe it's my firewall.
Is there any way I can disable my firewall but only for terraria?
I really don't wanna run the risk of my compy getting a virus for the sake of hosting a server.
don't disable it. you can make exceptions in your firewall for certain programs. if you're using windows:
start > control panel > windows firewall > "allow a program or feature through windows firewall" (top left of screen)
click "allow another program", select terraria
if you don't use windows, I can't help you with this, sorry.