Using Port 3390 on Remote Desktop Control

I changed an XP machine to use port 3390 for Remote Desktop Control.

I can easily connect within our network to the machine's internal IP address.

But from outside using our external ip address:3390  - I cannot connect.

In the router, I put in 3390 in the port forwarding, using UDP and TCP.

What do you think I missed?
Who is Participating?
Rob WilliamsConnect With a Mentor Commented:
In my "humble" opinion, you obviously know how to set this up as you have port 3389 working on one machine. Therefore, I would assume you have done 3390 correctly. The one thing that is different is the registry changes and you have verified that. However, as I mentioned earlier the Windows firewall (or any other such as Symantec, ZoneAlarm, McAfee, etc.) would have to be configured manually for port 3390. If you haven't done so already switch it off, for testing, or add the new port exception. To do so open he firewall; control panel | Windows firewall | Exceptions | Add a port
Make sure you you also click change scope and select "any computer (including those on the Internet)"
Rob WilliamsCommented:
There are a couple of ways to do it on the router.
-If you can redirect external ports to internal ports you can avoid having to make the registry changes on the XP machine, to change the listening port on the workstation. You simply direct external port 3390 to internal <appropriate IP> and port 3389.
-if you don't have that option redirect port 3390 to <appropriate IP> port 3390

Neither answers your question though <G>
You can test your port forwarding by going to from the appropriate computer and testing for the appropriate port.

If blocked, verify you do not have any ports blocked by a firewall such as the Windows firewall. When you enable remote desktop it automatically configures the firewall for port 3389, but not 3390. Test by disabling the firewall. If resolved re-configure the firewall on that computer for that port.

One other possibility; assuming you have port 3389 configured and working properly your router configuration method is correct but numerous people have reported problems with using side by side ports on some SOHO routers. Try switching to port 3391, i.e. space them out by at least 2 ports.
nprignanoTechnical ArchitectCommented:
depending on the router, you may also have to allow traffic on port 3390.  i know for a fact that you have to do that for watchgaurd firewalls, so its a possibility.

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I agree with RobWill on testing the port with something else just to make sure it is getting through...and then go from there.

You can also use the TinyWeb server (a less than 40k web server you can configure to use any port) and a web browser to easily test ports. There are simple, easy to follow instructions here:


hi pal
Okay i had this issue in my own machine.
Reason: You cannot connect because
1. windows firewall issue or other firewall installed
2. Unisntall any proxy servers running in the machine .

Solution : If the ports are forwarded correctly then
1. First get your internet ip of the server machine by
2.If your are connecting from outside the network the best option woul be "remote desktop web connection"
The article link is here
The above link is the best way to connect computer from external network
Also check
If any doubts after reading the above link please let me know
But i am sure the above solution will resolve all your problems


If the above solution helped to solve  your problem please appreciate my work by providing points  

Sorry it is
what model/kind of router/firewall are you using ---this would be helpful in solving the issue..
jimmysupportAuthor Commented:
I am using Windows XP Remote Desktop Connection.

I am using a Belkin Pre-N Router.

I have one machine using the default 3389 - and it connects from off premise just fine.

I changed the port in the Registry to 3390 and tested in within the building and it works fine thorugh XP Firewall and all.

the article by Northup is almost exactly what I did to make the first one work.

This one was done the same...except I changed the XP Machine to listen on 3390.

The site is very nice, but offers no solution to this issue, thanks, though for looking at my issue.

It may be the "spacing out" issue, I will have to try that.

what is the ip address you are using  to connect the computer from external network. Is it the inernet ip
did u read the above link on setting
"Remote Desktop Web connection"
jimmysupportAuthor Commented:
Yes, read the article..and as I said I did almost everything exactly as he wrote for the first connection and the only thing different on the second is that i set the listening port to be 3390.

Yes, I am using the Internet IP - when I use it for the 3389 machine, it works fine, when I add the :3390 it won't connect.

But, inside the building - it does.
You have to assign the computer a static IP in the range of the x.x.A.X domain structure, and whatever that IP is, you have to forward the port in the router to that static IP.  Also in the IP setup of the system with the static IP, you must specify the gateway as the IP address of the router, once again, must be static.
okay in your tcp configin network connections  have u added static ip ,subnet and the gateway ip to the computer also add prefered and  alternative dns server . Also give particular ports access from windows firewalls. I had the  exact same problem after a lots of trial and error method i had it solved.Also i had the problem wtih port not getting forward so i set it in DMZ zone and it worked. You can also try putting the router in DMZ zone and try to access from external network. Also there is a possibility of isp blocking particular ports.

jimmysupportAuthor Commented:
I changed it to 3391 - just to be safe..not that.
It was your idea Robwill.....I added the port to the Windows firewall...I put
Name Remote - 3391 tcp
and also
Name Remote2 -3391 udp
I also added in the internal address as running the RDC  under the LAN tab of the Windows Firewall.

Thanks everyone for your ideas. Best $50 I ever spent!
Rob WilliamsCommented:
Thanks jimmysupport, glad you were able to resolve.
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