FTP with WININET.dll Problem (Visual Foxpro)

Hi to everybody, I have a very strange problem here.
One of my client buy a “new” software. The problem is that not work with mikrotik, and wor fine with tplink or linksys.
I make a zoom to the code, And notice that the software login fine into a FTP server, but has error when try to upload.
I ask for the ip/user/pass and test it on Filezilla, this work fine. (ip/user/pass work fine). And why not work the software??
The owner of the software tell me that they use WININET.dll in Visual Prox. For that reason i see that the problem is that library.
I try this software in my home with a mikrotik and have the same problem. If I change the router for a linksys work fine.
In my home I hace a simple connection pppoe and all for default. I run the default script in mikrotik.

Is this a Mikrotik bug?

Now I test in a RB3011UiAS-RM, and work fine. The problem are the 3x 951G-2HnD
Any idea?

Probably conntrack FTP helper is turned off or behind dual NAT. Winnet FTP uses active mode (requires open port) by default.

user bug.

thank for answer!!

by default work fine in RB3011UiAS-RM
by default not work on 3x 951G-2HnD
by defoult work fine in linksys or tplink
why is a user bug? I disable all default rules in “/ip firewall filter”


Only one WAN (pppoe)
/ip firewall nat
add action=masquerade chain=srcnat out-interface-list=WAN
/ip firewall filter
Disable all rule, all work fine except this software and the FTP

/ip service
set telnet disabled=yes
set ftp disabled=yes port=21
set www disabled=yes
set ssh disabled=yes
set api disabled=yes
set winbox port=12312
set api-ssl disabled=yes

/ip firewall service-port
set ftp disabled=yes
set tftp disabled=yes
set irc disabled=yes
set h323 disabled=yes
set sip disabled=yes
set pptp disabled=yes
set udplite disabled=yes
set dccp disabled=yes
set sctp disabled=yes

This is expected as you’ve disabled the conntrack helper.

/ip firewall service-port
set ftp disabled=yes

Yes i try it disable that. Now I downgrade to 6.40 and the problem keep :S

Some new idea?