FTP Cannot Connect with Sprint Mobile Broadband

Darr247,
   Thanks for the reply. I have tried to connect to several different FTP servers (of my own web sites on commercially-hosted ISPs such as pair.com, etc.).  As mentioned in my question, it all works perfectly when using a DSL modem with a Cat5 cable to my laptop.  
     However, when I switch to getting online with Sprint Mobile Broadband (Novatel Wireless Ovation U727 USB Modem, using Qualcomm 3G CDMA), suddently FTP cannot connect to anything.  
      I tried 3 different FTP clients (WS_FTP, Leech FTP, and WebDrive). Same story for all 3: socket error or "failed to connect."
     Could the Sprint Wireless network be blocking port 21 somehow?  I know you were able to do it with a Merlin S720 card, but maybe the Ovation U727 works differently.  What else can I try?

Some providers are blocking some protocols . Anyway, try the connection by using a browser or enable passive mode in FTP Client.
There is a method to check if is your "box" or not : download a thin FTP server  ( like ftpserv ) and connect to him in "loopback" mode ( not to 127.0.0.1 but to IP assigned by router ).

gnegrota,
    I was not able to connect to the ftp sites via the browser, either. (But see comments below.)

Darr247,
    I didn't realize the Windows firewall was on. I'm sure I had turned it off when installing worm protection in Norton AntiVirus.  Anyway, I discovered Firewall was On. When I turned it off, I was finally able to connect through FTP.  Maybe the Sprint Mobile Broadband software had turned on the firewall, unbeknownst to me.
    Probably, I actually want to keep the firewall on, but allow the FTP software to get through it.  I tried opening TCP port 21, but that did not make any difference.
    What port should I open in the Windows Firewall to allow all FTP clients to get through?

In Windows Firewall applet you must define as exception the program that communicate in FTP, In Norton is somehow the same.
If you need to be FTP Server, it's another story . Let me know !

btw, FTP service are working on 2 ports : 21 TCP for connection and 20 TCP for Data Sessions.

By the way, I noticed there was already a firewall "exception" set for WebDrive; and I also manually set an exception for WS_FTP, but that did not help.  Neither one can connect when Firewall is On, even though there is an exception for them. Short of turning Off the firewall, what other exceptions or port openings should I do?

Some Antivirus software are blocking the FTP communication ( 'coz are a wellknown method for worms and tojans, same as for TFPT ). Check the connection with ALL Antivirus protections OFF, just for debug.
 

gnegrota,
 It is definitely Windows Firewall, not Norton AntiVirus that is blocking FTP.  I opened both ports 20 and 21, but it still can't connect. I also made exceptions for WS_FTP.

WindowsFirewall have logging capabilities. Enable it and post the related lines here, pls. ( the file is under %WINDIR%\pfirewall.log , where %WINDIR% is something like C:\Windows )

I guess I made a mistake about Norton. I had turned off automatic virus protection, and assumed that had also turned off Worm Protection. But actually, Worm Protection was still on. When I turned it off, FTP was able to connect (even though Windows Firewall is On).  I tried making an exception for WS_FTP in Norton Worm Protection, but that does not make any difference.  I also opened inbound and outbound ports 20 & 21 in Worm Protection, but that did not make any difference, either.
     So far, here is what works:  a) completely turn off Windows Firewall; or b) completely turn off Norton Worm Protection.  Either one of those seems to work, even if the other one is On.  (FTP works while Firewall is On, if Worm Protection is Off.  FTP also works while Worm Protection is On, if Firewall is Off.)
    Now I'm going to try enabling the logging in Firewall, as you suggested before.

:D Ok !
Glad to help you to rezolve the issue !
The config is as the following: Exception in both ( WinFirewall and Norton) for desired client and FTP protocol in Outbound, the rest in On !
Have a nice day !

Here are the results of the Firewall log while attempting to connect through FTP (file attached).

Configuring an exception for WS_FTP in WinFirewall and Norton, and also opening ports 20 & 21 in both, has no effect. It does not help.  So far, the only way to connect FTP is to completely turn Off either one of those protections (either one or the other).  There should be a way to use FTP without having to turn off WinFirewall or Norton Worm Protection.

There is no FTP session and no DROP . You try an FTP after you enable the logging ?
 

Somehow, Norton does "penetrate" in Windows enviroment and this are creating sometimes problems with connections. Moreover, a double packet filtering is unpredictable .
Let both enabled ( with your client in exceptions for both ) , but enable PASSIVE mode for client session .

=== Something foulish, but :-D : Add Norton AV in WinFirewall exceptions .

Yes, I definitely tried an FTP connection after enabling firewall Log.  It seems strange that the log does not show any FTP issues.
    Passive mode has been enabled all the time in WS_FTP, so that is not the problem, either.
    I think the solution may be to turn off WinFirewall only for the Sprint Novatel Wireless connection (but leave it On for local / DSL cable connections).  I assume that Norton Worm Protection would still be active on that connection, even if I turn off Firewall for that one connection.  Doing it this way seems to fix the problem.  Does that sound secure enough?

I did not have to disable norton (NIS2009) at all to use WS_FTP... it popped up a key logging warning when I entered my username and password in it to my FTP site, but I don't recall it blocking the connection itself.

What version of norton are you using, and do you have its firewall in learning mode?

Darr247,
    This is Norton AntiVirus 2006, with Worm Protection enabled.  As far as I can tell, there is no learning mode in that version.
    Strangely, I'm able to connect to FTP as long as one OR the other is disabled: either NAV Worm Protection, OR Windows Firewall.   Since NAV says WinFirewall is unnecessary while using Worm Protection, I hope I can rely on the Worm Protection for sufficient security, and I'll just turn Off WinFirewall for the Sprint Broadband Wireless connection (but I'll leave Firewall on for my other connections).

Thanks for your time and expertise.