I have a 500Mb external hard drive connected to my Archer A7 via USB. I'd like to be able to access it via FTP remotely.

I have set it up for sharing in: Advanced > USB Settings > Sharing Access

I have set up Dynamic DNS using the TP-LINK service and I have a domain name.

I can ping the domain name and get a response (and get the IP address)

When I try to connect to the hard drive via FTP client I get an error.

In WinSCP using FTP/port 21 I get "No connection could be made because the target machine actively refused it."

I also tried FileZilla and get "Connection refused by server"

I feel ike I am missing something very simple. Has anybody else set this up successfully? Any ideas?

I seems odd that I can't just give the connected USB hard drive a static IP address (e.g. 192.168.0.200), forward the port I need and be done that way?

Anyway, any advice very gratefully received.