on my installation, 2.4.3. release p1
since I found it difficult to go out on FTP sites, with continuous jumps and disconnections,
I installed the FTP Client Proxy package

In practice everything works perfectly if I access FTP outside my network (on the Internet)

Now I had to create a VPN in IPSEC, on which I have to contact an FTP.
And here the problem starts.
With FTP Client Proxy active I could not reach the machine on the VPN and there were not even any connections.
Then I tried to disable the service, and in fact reach the machine, but as well as those on the internet jumps continuously and the connection is not absolutely stable.

The FTP client is active on my LAN and no other parameters are changed.
But if you activate it, no more traffic goes out in VPN.

What escapes me?

Thanks for every help