RETR downloading zip File from ftp not writing - python-3.x

Question

I am trying to donwload a huge zip file (~9Go zipped and ~130GO unzipped) from an FTP with python using the ftplib library but unfortunately when using the retrbinary method, it does create the file in my local diretory but it is not writing into the file. After a while the code runs, I get an timeout error. It used to work fine before, but when I tried to go deeper in the use of sockets by using this code it does not work anymore. Indeed, as the files I am trying to download are huge I want to have more control with the connection to prevent timeout error while downloading the files. I am not very familar with sockets so I may have misused it. I have been searching online but did not find any problems like this. (I tried with smaller files too for test but still have the same issues)
Here are the function that I tried but both have problems (method 1 is not writing to file, method 2 donwloads file but I can't unzip it)
import time
import socket
import ftplib
import threading
# To complete
filename = ''
local_folder = ''
ftp_folder = ''
host = ''
user = ''
mp = ''
# timeout error in method 1
def downloadFile_method_1(filename, local_folder, ftp_folder, host, user, mp):
try:
ftp = ftplib.FTP(host, user, mp, timeout=1600)
ftp.set_debuglevel(2)
except ftplib.error_perm as error:
print(error)
with open(local_folder + '/' + filename, "wb") as f:
ftp.retrbinary("RETR" + ftp_folder + '/' + filename, f.write)
# method 2 works to download zip file, but header error when unziping it
def downloadFile_method_2(filename, local_folder, ftp_folder, host, user, mp):
try:
ftp = ftplib.FTP(host, user, mp, timeout=1600)
ftp.set_debuglevel(2)
sock = ftp.transfercmd('RETR ' + ftp_folder + '/' + filename)
except ftplib.error_perm as error:
print(error)
def background():
f = open(local_folder + '/' + filename, 'wb')
while True:
block = sock.recv(1024*1024)
if not block:
break
f.write(block)
sock.close()
t = threading.Thread(target=background)
t.start()
while t.is_alive():
t.join(60)
ftp.voidcmd('NOOP')
def unzip_file(filename, local_folder):
local_filename = local_folder + '/' + filename
with ZipFile(local_filename, 'r') as zipObj:
zipObj.extractall(local_folder)
And the error I get for method 1:
ftplib.error_temp: 421 Timeout - try typing a little faster next time
And the error I get when I try to unzip after using method 2:
zipfile.BadZipFile: Bad magic number for file header
Alos, regarding this code If anyone could explain what this does concerning socketopt too would be helpful:
ftp.sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
ftp.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 75)
ftp.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 60)
Thanks for your help.