# Solved: Working With My Motorola SB5101



## mystic54 (Oct 25, 2004)

Ever since I moved into an apartment a few months ago, I have been dealing with NAT related issues on my 360 due to my new internet setup. Time Warner (Roadrunner Cable Internet) provided a Motorola SB5101 modem which appears to have almost zero configuration settings on it when I go to 192.168.100.1. I did notice that on page for the modem, it says DHCP is enabled which is definitely a problem because my router is supposed to be doing the DHCP. 

I just spoke with a Time Warner rep and there is no way I can configure the modem (like I thought) so it seems that I'm limited to just configuring my Linksys WRT54GL. How can I put my router into a "bridge" type mode while still providing wireless routing capabilities? 

My main focus is on getting my Xbox 360 to have an Open NAT setting. If you need to know any more information, ask. Thanks


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## JohnWill (Oct 19, 2002)

The SB5101 is a plain cable modem, so it's already in "bridge" mode. Any port forwarding issues are due to either your router or the ISP. Here's the guide to configuring your router to use XBOX Live: http://portforward.com/english/routers/port_forwarding/Linksys/WRT54GL/Xbox_Live_360.htm


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## Soundy (Feb 17, 2006)

The modem has nothing to do with your problem *IF you have everything connected properly*. The modem's DHCP provides your "outside" IP to the router's WAN port only - if you turn that off, your internet connection won't work. Any devices behind the router should be getting an internal IP (192.168.1.*) from the router's LAN side (including wireless).

Simplest way to make the 360 work would be to find the router's DMZ option, and set it to the 360's IP.


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## mystic54 (Oct 25, 2004)

Soundy said:


> The modem has nothing to do with your problem *IF you have everything connected properly*. The modem's DHCP provides your "outside" IP to the router's WAN port only - if you turn that off, your internet connection won't work. Any devices behind the router should be getting an internal IP (192.168.1.*) from the router's LAN side (including wireless).
> 
> Simplest way to make the 360 work would be to find the router's DMZ option, and set it to the 360's IP.


I've tried the DMZ option but the 360's IP is not static. I've tried changing everything on the router side of things to static but something was erroneously changed along the way because the Internet didn't work in the end.

Edit: I've successfully setup a static IP on my computer where I'm able to open ports just fine, my 360 is another story. I gave the 360 a static IP and then used the same subnet mask, default gateway, primary (and secondary) DNS servers.

Primary DNS Server: 192.168.254.254
Secondary DNS Server: 76.85.229.110

Using that setup and forwarding the appropriate ports for the 360 to my 360's IP still results in a strict NAT. If I put the 360 in the DMZ, it is open. I would just put it in the DMZ but there are two 360's on my network so I need to figure out how to get the port forwarding to work for at least one of the 360's.

Edit: Never mind, it might be working. Thanks for the help guys.I've set up static IP's tons of times before so I'm really not sure what I was screwing up before I posted because I was already doing all of these steps but must have just had one tiny setting wrong.


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## Soundy (Feb 17, 2006)

Theoretically, the 360's IP should never change as long as it's connected. This is an issue I've long had with LinkSys routers, that they tend to randomly refresh constantly-connected machines with new IPs, and many don't have a reserved-DHCP option. Looking at the manual online, I don't see one on your model, either.

What you can do is this: whatever range you set for your DHCP server (100 to 150, for example), hard-code the upper number into your 360 (192.168.1.150, for example). Be sure to enter the correct Netmask, Gateway and DNS IPs as well (should normally be 255.255.255.0, 192.168.1.1 and 192.168.1.1). Then set the DMZ to that IP (in this example, 192.168.1.150).


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## TerryNet (Mar 23, 2005)

Why assign a static IP within the Dhcp server's address range? That's just asking for trouble, even if the risk is low because of the way IPs are dynamically assigned. Use a static IP outside the Dhcp server's range and avoid duplicate IPs.


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## mystic54 (Oct 25, 2004)

I'll create another post for my friend's 360 who is using a slightly different setup.


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## Soundy (Feb 17, 2006)

TerryNet said:


> Why assign a static IP within the Dhcp server's address range? That's just asking for trouble, even if the risk is low because of the way IPs are dynamically assigned. Use a static IP outside the Dhcp server's range and avoid duplicate IPs.


Because some routers won't let you assign port forwarding and DMZ destinations outside their defined DHCP range. There's nothing like assigning a machine 192.168.1.151, then going to forward a port to it, only to be told it's an "invalid IP".

Actually, the best solution here is to ditch the LinkSys and get ALMOST ANY OTHER router that actually has static/reserved LAN IP capability.

Or if you're feeling super-ambitious, re-flash your WRT with DD-WRT or any of a number of other third-party firmwares that give it enhanced functionality.


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## JohnWill (Oct 19, 2002)

I've never run across the issue where I couldn't port forward outside the DHCP address range, though I don't doubt it exists if you've seen it.  I wonder what router manufacturer would be that stupid?


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## Soundy (Feb 17, 2006)

I've seen it on one or two D-Link models, which really amazed me, because most of the newer ones have some of the most configurable port forwarding I've found anywhere.

I've also seen some (don't remember which, might have been an old Belkin) where you had to select your forwarding destination from a drop-down list that contained only the IPs it found in its DHCP table.


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## JohnWill (Oct 19, 2002)

I can believe it on a Belkin, I'm totally underwhelmed with their products! I've had some pretty ancient D-Link routers, a DI-614+ and a DI-524, and both of them had very flexible handling as well as DHCP reservations.


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## Soundy (Feb 17, 2006)

I know, my first wireless router... or first router at all, for that matter, was a DI-614+. I still have it; it still works. This was actually a newer one, one of the WBR models, I think. That's what really blew me away. It has all the great forwarding features, like being able to specify comma-separated multiple ports or port ranges, but it would only let you assign them to addresses within the DHCP range.


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## JohnWill (Oct 19, 2002)

Very odd. I wonder why they removed that capability AND got rid of DHCP reservations as well?


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## Soundy (Feb 17, 2006)

They didn't get rid of the DHCP reservation... but it means you can't forward to a manually-assigned address. Example from the one store that I used one of these: I used hard-coded IPs on the DVR and network cameras outside the range of the DHCP server, for the sake of organization (camera 1 = *.0.201, camera 2 = *.0.202, and so on) and needed to be able to forward to those addresses. Couldn't do it. I had to add that range to the DHCP pool, let the cameras grab IPs, then manually edit the reservation list so the appropriate MAC got the appropriate IP.


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## JohnWill (Oct 19, 2002)

Well, at least you could do it.


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## TerryNet (Mar 23, 2005)

> Because some routers won't let you assign port forwarding and DMZ destinations outside their defined DHCP range.


Thanks, Soundy. I had not heard that before.


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## Soundy (Feb 17, 2006)

JohnWill said:


> Well, at least you could do it.


Yes, but I'm a genius - your average user would be lost!


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## JohnWill (Oct 19, 2002)

Soundy said:


> Yes, but I'm a genius - your average user would be lost!


Save me!


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