Friend cant join server

[chrissybhoy001]

so I joined my own Ip4 address to join my own server. My question is, how does my friend join?

[1wsx10]

i got the same issue. im hosting on a linux laptop in my room next to me, i connected through the lan, and port forwarded the same address on 9000, but my friend can't connect through my public ip

edit: they just connected

their words: "i just left it saying 'cant find server address' and it just loaded the maps"