Please post session log file both from the home wifi and hotspot.
Did he test the connection with any other FTP client?

Hello, we're a team of FiveM Server Devs who have been building a FiveM Server and one of our devs is having a weird connection issue. Basically, what has been happening is when our friend tries to connect to the FTP server, even with nobody else connected he is unable to on his home wifi and can only connect using his hotspot on his phone. We weren't sure if this was because of WinSCP, his computer, internet company or Zap Hosting so he's talked with Zap to no avail, he's tried talking with Spectrum and they couldn't find anything wrong with the internet/router and we've removed every firewall possible and allowed the program through his PC in any way possible and still he gets denied access or remote directory reads until timing out, so we're coming here in hopes of getting the needed help. Any suggestions will be greatly appreciated! We've been so confused!