Error 530 when trying to connect to an FTP server on Fedora Server

I want to build a standard FTP server on Fedora Server 39. This is the only function of this server.

Brand-new install, then installed vsftp and followed the various steps (FTP user, firewall config, share, mount etc.).

However I can’t connect to this server (from Win11 command prompt; same network). Whatever I do I get a 530 login incorrect error. Have temporarily disabled SELinux, the FTP user details are correct.

What could this be?

You can start with the most basic FTP server configuration to isolate possible problems.
Try permissive SELinux mode, run the client on the server host, avoid involving extra mounts.
When you verify that it works, gradually customize the setup and test it after each change.