I think you could be right, and the FTP implementation is buggy. Or it could be just like many FTP Server implementations, and support a limited range of commands, requiring the FTP Client software to work out what the Server can do, and use the approporiate commands to achieve the result required. Also, some FTP Servers just seem to prefer particular FTP Clients.
Anyway, I had a play using the worst, lowest common denominator FTP Client; the Windows 7 ftp.exe Client run in a Command window. This client doesn’t support Passive connections, which would be better, but then the MPW FTP Server may well require an Active connection. Certainly that is implied in the User Manual, on page 32, where it says that Passive should be disabled. Strangely I was able to change the MPW FTP Server to Passive mode though, by issuing the “quote PASV” command from within the ftp.exe Client. Not that it did me much good, since the Client can’t use Passive mode.
I was able to connect straight away, and use a few commands, such as PWD, CD, MKDIR, but I was not able to list directories using LS or DIR, and I coouldn’t send or receive files using PUT or GET. I kept getting the “425 Use PORT or PASV first.” error message.
However, when I was nearly ready to give up, I quit the FTP Client using the “Bye” command, and then reconnected . . . and it started working.
I could list directory contents, and transfered a file to the MPW using PUT, then renamed it on the MPW and copied it back using to my PC using Windows Explorer, and the file was intact.
Just to be sure, I installed the FileZilla 3.10.2 FTP Client and did a few transfers with that, in both directions, using drag and drop. It worked fine, and fast. No issues. Also, FileZilla was set to work in Passive mode, with fallback to Active mode, but it didn’t appear to do that. so the MPW FTP Server must support Passive mode. FileZilla did report that the MPW FRP Server was an “Insecure server, it does not support FTP over TLS.”
So I have to conclude that the MPW FTP Server works fine, if with a few idiosyncrasies.