Press Windows Key + R, and type CMD and hit enter, then type ipconfig /all and it will be what is next to IPv4 Address. that will be what you put under LAN Users in port forwarding. It looks like you are only port forwarding inbound connections, and not outbound. make sure to port forward both in and outbound. Try using a port tester website such as http://canyouseeme.org/ Make sure your server is online and running, and check the port. If it still says your port is closed, try allowing the outbound and inbound port in Windows Firewall.
EDIT: yes, the # thing is called a comment. remove the # infront of sv_master. However I don’t think that sv_master is a thing anymore, because it’s not listed in the default server.cfg on the FiveM site, https://docs.fivem.net/server-manual/setting-up-a-server/#server-cfg I think you just have to have sv_hostname "FiveM Server" Also, make sure you have endpoint_add_tcp "0.0.0.0:30120" and
endpoint_add_udp "0.0.0.0:30120" at the top two lines of your server.cfg.
- Right-click the Start button.
- Click Search .
- Type Windows Firewall .
- Click Windows Firewall .
- Click Advanced settings .
- Click Inbound Rules in the left frame of the window.
- Click New Rule… in the right frame of the window.
- Click Port .
- Click Next .
- Click either TCP or UDP .
- Click Specific local ports .
- Type a port number . (In this case, you will open port 30120)
- Click Next .
- Click Allow the connection .
- Click Next .
- Click any network types you’d like to allow the connection over. (private and public, if you want public)
- Click Next .
- Type a name for the rule. (example: FiveM30120out)
- Click Finish .