How do I let people connect to my listen server?

I’ve got a listen server up and running, and I want some friends to connect with it. However, they don’t see my server anywhere. How do I let 'em connect?

You need to portforward

Already done that.

sv_lan 0

Tried that.

you need to do sv_lan 0 before starting the server


Also, have they tried connecting through the console?

^ give them that IP

And what solved my problem was to forward the ports on both my router and my modem.

Edit: Assuming that you also have a router