Opening NAT - 3c857


I have this 3com 3c857 router, which i want to open the NAT so i can play on xbox live..

I searched everywhere and did find nothing.

Can anybody show me a tutorial on doing this?

Thank you very much.
21 answers Last reply
More about opening 3c857
  1. Can anybody help me with this?

    Thank you.
  2. Read section 6 (Configuration of LAN Parameters): and set it as a DHCP server. NAT simply means that you use a single Internet IP address and the router takes care of internal and external address translation. Common internal IP addresses are 10.x.x.x and 192.168.x.x.
  3. I did not find the section 6, your link redirects me to a google page.
    And my IPs are: (PC) and (Xbox 360) - NAT Moderate.

    Thank you.
  4. But if you click that google page, you'll download the manual from
  5. Ok, i read the manual and there is nothing about NAT configuration or so.

    I manually configurated the PC IP as and the Xbox360 IP as There is no support for UPnP in this router so now I don't know what to do.

    Do you know how to get the NAT open?
  6. It certainly is a very basic router, but why do you need UPnP?

    Look at Figure 11. Is how you have it setup? What's the IP address of the router? If you use static IP addresses instead of DHCP, then you have to specify the default gateway, i.e., the router IP address (by default it is

    Your router does NAT automatically; otherwise you wouldn't be able to access the Internet with a static or dynamic IP address that isn't routable (192.168.x.x). Therefore you can't enable or disable NAT since it's always enabled.
  7. Cable (Static:10.50.x.x) > Router (> PC (Tried both, not satisfyed - Manual - or Auto - > Xbox360 (Tried both - Auto/Manual On the xbox, when I test the conection, it says: You have a problem with the connection: NAT Moderate.

    UPnP I don't even know what it is, but on the xbox, it says as a tip to enable UPnP in order to open NAT.
  8. Let's say that cable static IP address is What IP address did you use on the WAN port of your router? It should be and it's LAN address is UPnP (Universal Plug and Play) just makes it easier for devices to communicate, but it isn't required if the router is configured correctly (and it wouldn't help is it isn't).
  9. But it is set that way, otherwise i wouldn't even be able to connect to the internet.
    It is WAN>10.50.x.x
    LAN1 (PC)>
    LAN2 (Xbox360)>
  10. If you can access the Internet and the Xbox doesn't work properly, then you need to set port forwarding for the following to

    * TCP 80
    * UDP 88
    * UDP 3074
    * TCP 3074
    * UDP 53
    * TCP 53

    UPnP would do that for you, but your router doesn't have that feature. Does it at least support port forwarding?
  11. Well, I don't think so, is that it?

    Well, if that's it, it does not work.

    What about DMZ? In DMZ Host IP, should I put the PC IP or the xbox360 IP?

  12. Don't use the DMZ. In the Virtual Server section, the DMZ is set to which basically denies access.

    As per the instructions, click New.

    Server IP address: (Xbox)
    Local Service: - Custom -
    Custom Service Name: Xbox (or whatever you want)
    Specify Custom Service Ports: 88,3074 (and you might need to also add 53)

    Is this what you've done?
  13. Yes, I did that.
    There's no how to specify if its a UDP or TCP port, but i enabled 53,88 and 3074. No success. Oh, there's no success either if I disable the router's firewall, does that mean something?
    Should I enable PING in the router?
    There's a Special Application option in the router, which asks me the trigger and the incoming ports, I don't know if that's useful.
    And, right now, it says on my xbox that my MTU should be at least 1364, and I'm below that..
  14. You can enable ping on the router. Your problems have to be with port redirection.

    There's a Special Application option in the router, which asks me the trigger and the incoming ports
    You lose nothing using it to configure port forwarding.

    Why is your MTU that low? It should normally be between 1450 and 1500 (only if you don't use PPPoE).
  15. What does "PING over the internet" do? What is it?
    I think my MTU was that low because Xbox Live is currently at maintenance, I'll wait for the xbox live to get back online and see if it's ok.

    The thing is, I don't know what are the incoming and the triggering ports.
  16. Quote:
    What does "PING over the internet" do? What is it?
    It allows to detect the availability of hosts. If I can ping a host and get a reply, then I know that host exists and that it should be live.

    The thing is, I don't know what are the incoming and the triggering ports.
    They should be the ones that are specified for the Xbox (53,88,3074).
  17. But which do I put in the trigger port line?
    And the incoming line?
    They cannot be repeated.
  18. Add each required port and forward it to the Xbox.

    Example from my Netgear router configuration screen:

    Service Name Xbox_88
    Service Type UDP
    Starting Port (1~65534) 88
    Ending Port (1~65534) 88
    Server IP Address

    Service Name Xbox_3074
    Service Type TCP/UDP
    Starting Port (1~65534) 3074
    Ending Port (1~65534) 3074
    Server IP Address

    Service name can be anything you want, at least on my routers. Apparently that's all that's required (port 88 UDP and 3074 TCP/UDP). The above configuration assumes that your Xbox has static IP address You might need to make configuration modifications on the Xbox (my knowledge of the Xbox is nil).
  19. Ok, the xbox live is at maintenance right now, so I'll reply again only tomorrow, when the service is back online.

    As for the configurations, on my router, you cannot select TCP or UDP (don't think it'll be a problem).
    And, with this configurations on, I'll have to delete my Virtual Server, because I cannot type a port on the virtual server and the same one in authorised applications. But I'll test them both tomorrow (have not tested yet the ports 53,88,3074 with DMZ off).

    And, just to add, on the Xbox, the only thing you can configurate is the basic: IP, mask, gateway and DNS.

    I'll be back tomorrow.

    Thank you very much for the help.
  20. Ok, just tried it and.. no, it does not work !

    As I said, not even disabling the router't firewall can make my NAT open. Shouldn't that mean something? Maybe it's not a router problem, I don't know..

    Any other suggestions?
  21. You could get a router that's on the Xbox compatibility list (UPnP, etc.) That should be easier to setup.
Ask a new question

Read More

Routers Xbox Live Networking