It worked for me..

I got it to work just fine. Once I found out that it was on port 2121.(cmd->ftp->open devicesipaddress :2121) Did a cmd ftp and connected just fine. Im using the ftp server version and dont know what the difference is between it and the 0.99C one.
Also wanted to add if your device goes to sleep it will not work. Has to be awake.
Ok, used WS-FTP ver 8. You have to not use anonymous as user(use a small user word say "test) with no password. Let the win ftp software prompt you to enter in username and password. Then enter the "User Id on remote host:" whatever you would like(say "test) without input on password. I also used this via the browser. ftp://anynamehere@yourdevicesIPaddress:2121 Both worked. This worked for me and I hope it will help you. OS 4.1 in use with WiFi.

zmynameismudd about FTP Server, v4.0