l o c a l h o s t : 3 0 0 0

The port number 3000 is not officially assigned by any application, but many different server software or application development platforms can use it on localhost by default. In terms of both TCP and UDP port, your thousandth port is usually down and unavailable. You can activate and use it whenever you want. Sometimes 2999 or 30001 port range can be used instead of this port. Especially in application development environments, platforms such as React, NodeJs, Wamp, Xammp, ISS on your local server use http://localhost:3000/ or http://127.0.0.1:3000/ by default because they are free. You can quickly access this address from the link above.

Can't access to http://localhost:3000/ address

First of all, if you are having trouble accessing, try whether this port is open or not. On Windows systems open Command Promt (cmd.exe) Run as Administrator and write "netstat -ab"

On Linux or Unix, you must usage the "netstat -tulpn | grep LISTEN" commant on terminal window.
If the port is closed, enable it and also allow this port number in the Firewall settings.

Connection Status

Local Hosting Server File Location & Connection Ports

Ports:
localhost:631 ⟷ localhost:4000 ⟷ localhost:5557 ⟷ localhost:11501 ⟷ localhost:3010 ⟷ localhost:3306

Folders:
localhost/wordpress ⟷ localhost/wordpress/wp-admin ⟷ http://localhost/mysql