426 Cannot retrieve. Failed. Aborting

For the first time I have had problems with downloading files from a server.
First of all it is a rather picky server, for instance demanding Active Mode.
Half of the times trying to log into the server I got the "Not enough socket" or some other socket error.
A couple of times I managed to log in but did not see any files.
Now I have managed to log in a few times, seeing the files but downloading gives this error message:
"426 Cannot retrieve. Failed. Aborting".
This only appears for a longer 4 MB file.

220 WELCOME TO #### SERVER
USER ####
331 Password required for ####.
PASS (hidden)
230 User #### logged in.
SYST
215 UNIX Type: L8
FEAT
211-Extensions supported:
CLNT
MDTM
PASV
REST STREAM
SIZE
211 End.
CLNT SmartFTP 1.5.988
200 "SmartFTP 1.5.988" noted.
PWD
257 "/" is current directory.
SIZE ##FILE NAME##
213 4372505
TYPE I
200 Type set to I.
PORT 192,168,0,33,6,161
200 Port command successful.
RETR #FILE NAME#
150 Opening data connection for #FILE NAME# (4372505 bytes).
0 bytes transferred. (N/A/s) (0 ms)
426 Cannot retrieve. Failed. Aborting

When I try downloading a small file from the same directory, everything works:

200 NOOP command successful.
NOOP
200 NOOP command successful.
SIZE FTP Video Downloading Instructions.doc
213 27648
PORT 192,168,0,33,6,169
200 Port command successful.
RETR FTP Video Downloading Instructions.doc
150 Opening data connection for FTP Video Downloading Instructions.doc (27648 bytes).
226 Transfer ok
27648 bytes transferred. (5,34 KB/s) (00:00:05)
Transfer successful.
NOOP
200 NOOP command successful.
NOOP

What might be the problem? It is a professional server probably used by dozens or hundreds of people every day.
And yes, I am in the global queue but won't the server get mad when I perform this failed download every 5 seconds for 30 minutes? That's when I decided to switch off the last time.