Gmod Server Not Showing In Server List

I have created a Garry’s Mod server and have the file on my desktop with srcds. When I start up the server it says

Connection to Steam servers successful.
   Public IP is 71.***.**.***.
Assigned anonymous gameserver Steam ID [A-1:9******67(**48)].
VAC secure mode is activated.

The server shows up on my LAN server list. My friends have looked up my server and not found it. When they try to connect to my IP it says “failed after 4 retrys”.

1: My ports are 27015-BOTH, 27016-BOTH, 27016-BOTH, and 27018-BOTH
2: I will not use Hamachi
3: sv_lan is 0

Allow those ports through windows firewall as well? It might be possible to use the P2P system Willox put in as well, not sure how to enable it by default though.

(See Edit below)
What does this site show, when you insert the ip and port of your game server into the url?

Edit: Nevermind, I thought because you put Server List in the title, you mean the global server list.

This is a common port-forwarding problem. Did you port forward on your router?