Wait, I used LOCALHOST and it doesn’t work. that means It doesn’t leave my computer. the router has nothing to do with this !
ssh localhost works, ssh localhost -p 4000 doesn’t,
and NO ssh [my public IP] works.
I don’t know whether my router blocks that port or not, nor how port forwarding works, nor if that’s what’s required ! For f***'s sake it’s so complicated, just for connecting two damn computers