HELP: Linksys Wireless Router, and Sprint DSL modem/router...

IsaacHayes

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Ok, I know networking, and this has even got me pulling my hair out. Doing this for a friend. They had a linksys wireless router hooked up all summer and it worked fine they said. Then it went down.
The devices in question is: Sprint SP-645M-A1 DSL modem/router, and Linksys WRT54G V3 wireless router.
I did the following:

1) Set the Linksys router's IP address to 192.168.1.10 from 192.168.1.1. (because the sprint modem was 192.168.1.1, so I figured they would be conflicting)
2) Manually put in Sprint's DNS server IP's in the Linksys router as it was not picking them up from the Sprint Modem/router.
3) I also had updated the firmware on the linksys before all this.

I have not updated the Sprint firmware, not sure how to do that either or find the files for it.

I dont' understand why would it work for several months, then quit? Why would it even work at all with the same IP's on both devices?

The Linksys works great on my Cable modem, so I think it's working fine. But when on the sprint modem it doesn't. You can reset everything, renew ,etc and it will work for a while, then 5mins later, nothing. Sometimes you can ping places and resolve dns, but not get to a website. There is one ethernet connected PC, and one wireless laptop connected to the linksys. Tonight when I came to work on it, I could not even get the linksys to respond via http, I had to reset it.

When you connect the modem directly to the desktop, it works great, and is very fast too.

It seems the Linksys doesn't like the Sprint m/r or vise versa.
It worked fast and responded fast on my cable modem (I have a linksys myself on my cable modem, without the wireless too.)

Am I missing something here? Whats going on, and why does it work for a short bit then go down? I did a full virus/spyware scan on both comptuers too BTW. I did change the MTU on the linksys from "automatic" to 1500 before I left tonight, as that's what the Sprint m/r is using. Not sure if that will make a difference or not. I'm out of ideas...

Any help would be appreciated!!

-Isaac
 

fluorescent

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try using the clone mac address feature on the Linksys. Use the mac off one of the PCs.
 

turbodog

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Your mtu is too high. I have seen that cause problems.


Sprint *could* have remotely upgraded the firmware. That would explain why it quit working.


The ip of sprint and linksys DO NOT MATTER if you're plugging the sprint into the linksys's WAN port.


Here's a thought. If sprint really is a router also, with nat/firewall/etc. I assume it issues dhcp addesses. Disable dhcp on linksys. Set linksys for 1 number (on the "D" octet) off from the sprint. Plug sprint into the normal network ports on linksys, NOT the wan port.

This way you can access both devices via web interface. But your linksys is really only acting as a hub and a wireless base station.


But you mtu is still too high. 1500 is really high, and I don't care what kind of connection you have.

Also, I tried to best interpret what you wrote. But you were a little vague on which ips go with the internal network and external one. It would be nice to know:
1. if sprint unit really is router
2. sprint issues ip via dhcp?
3. wan ip of linksys
4. lan ip of linksys
5. linksys IS set for automatic connection, right?

If linksys is not getting dns from sprint, the linksys may be booting up before sprint box does. Also, I have seen modems NOT reissue ip addresses more than one time after they were turned on. You might have to reboot spring EACH time you make ANY changed to linksys.
 

IsaacHayes

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fluorescent: tried that. No effect. It's not like my cable modem which does require a single mac address.

TurboDog:
A) So I should telnet into the DSL modem and find a way to change it's MTU to something lower? Not sure if it has a setting for that, but I cant remember all the menus it had. The linksys detected that MTU from the sprint box.

B) Yes it issues DHCP IP addrs, starting at 192.168.1.2 Client IP pool is set to "1", I tried to change it to anything higher, but it will only accept "1" or it says invalid number ??? So I'm not sure if it will release more than 1 IP address... I was going to plug the sprint into the switch ports on the Linkssy and do that, but I couldn't get the sprint to accept a value more than 1... so I scratched that idea.


Answers:
1) Yes.
2) You telnet into it via IP: 192.168.1.1. (note you have to have it plugged into the PC as you can't telnet through the linksys to get to it). It has DHCP, etc and starting IP it sends out is 192.168.1.2.
3) Wan IP of Linksys is 192.168.1.2 as assigned by the sprint box.
4) Lan Ip of linksys it serves DHCP addys starting at 192.168.1.100.
5) Yup.

The sprint box will issue IP's all day long when connected to a PC and you do ipconfig, /renew/release.

This link shows how to setup a linksys that they provide, but it's a little vauge and it must have pre-set things by sprint as they say the one that is bundled with the 645modem has an ip of 192.168.2.1, which normally default on a linksys is 192.168.1.1
This link shows how to on bundled linksys/sprint
The linksys my friend is using was not purchased through sprint.

....
 

IsaacHayes

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Hmm. Something just occured to me. I couldn't change the IP client pool in the sprint router to anything other than 1 because the subnet mask was set to 255.255.255.252. I forgot about that. That would mean 192.168.1.3 would be the broadcast address, so there is only one usable host. I can change that to 255.255.255.0 and then change the IP pool to a larger number. Then turn off DHCP on the linksys and plug the Sprint into the LAN switch ports on the Linksys and see what happens.

BUT that still doesn't answer the question as to why this won't work with the sprint going through the WAN port on the Linksys... hmmm :shrug:
 

Diode

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That's a strange setup. The WAN network on the Linksys is 192.168.1.0/24, but then the same network is used on the LAN side? It seems like you should pick a different network for the LAN side, say 192.168.2.0/24.

After that, you need to ensure that all computers use 192.168.2.1 (as an example) as the gateway. In addition, the gateway on the Linksys should be 192.168.1.1 (IP of the Sprint router).

So the topology would look like this:

----192.168.2.0/24----[Linksys]----192.168.1.0/24----[Sprint]----Internet
 

Lightmeup

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How long is the router's lease set for? If its lease expires and the modem doesn't issue a new one it'll be dead until then. Check modem to make sure it's renewing the router promptly. Is this setup using pppoe? If so, where is it being done?
 

turbodog

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Even if the sprint doesn't issue more than 1 ip, you can still use it that way.

Just set static ip addresses on everything. Point them to the sprint box as the gateway, put in dns, etc. No wait.... you'd have to modify the subnet on the sprint to do that.

You might be better off buying a retail dsl modem/router/wireless all-in-one unit. I mean, he's getting free advice and help; it's not too much to ask him to spend a few bucks for some new hardware.
 

IsaacHayes

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Diode: hmm. I might try that.
Litemeup: no pppoe. It dies after like 5mins so I don't think the lease expires that fast.

turbodog: actually I'm getting paid to do this, it's my hairdressors house setup that her son is using.. .. I see sprint uses linksys setup so there must be something else wrong here... What MTU do you suggest BTW?

I think I'll try setting the linksys to 192.168.2.1 and see what happens. If problems still I'll try to make the linksys a switch and make the DSL modem pump out more IP's....
 

gadget_lover

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It sure sounds like an arp cache expiring. The linksys is probably using a wide open broadcast when it sends it's bootp (or dhcp) request, and is then given a restrictive netmask and an address that conflicts. Further arp requests on the WAN link shoudl fail. (I think. It's late)

It sounds like the linksys WAN should be set to address 192.168.1.2.
The gateway for the linksys would be 192.168.1.1

It sounds like the linksys needs to do NAT.

It sounds like the linksys needs to use 192.168.2.0/24 for the inside net. 192.168.2.1 for it's internal address.

192.168.2.1 would then be the gateway for the PCs.

192.168.2.1 would be the DNS source for the PCs OR they could have Sprint's DNS.

5 will get you 10 that SPrint changed the DSL modem config at some point, changing it's address from something like 192.168.100.1 to 192.168.1.1 and counting on the magic of DHCP to handle it.

I don't really understand why they would use a netmask of 255.255.255.252 for an internal net. They are deliberately natting AND restricting the internal net to one PC. I would have thought they would just use a bridge router and give the PC a routable address. On the other hand it makes it easier for the helpdesk. Every one has the same IP address (as far as they know).

Daniel
 

IsaacHayes

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Daniel: Yeah I'm going to try 192.168.2.1 first.

I just kind of ran out of ideas tonight and got burned out on it. It took me forever to even be able to log into the router. I had to do a full reset on it. So something is either bad with it, or it's getting severely confused!! I'm betting on the later, because it worked fine when I brought it to my house one time. worked all night and day...

Thanks everyone. I'll keep this thread updated if I have anymore problems /cant get it figured out still...
 

StevieRay

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Isaac,

When using a DSL modem with a linksys router you need to set the modem in the "Bridged Mode."

Then log in to the Linksys and set it to PPPoE.

I would reccommend setting both to factory defaults first and then setting as described. Then power eveything down. Plug in DSL modem first until it connects, then plug in router, then boot computer.

It should work. If not, linksys has great tech support and should should be able to help.
 

AJ_Dual

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That's what I was going to say. Is there a PPoE password that has to be put into the Linksys? Most DSL providers (especialy telcos) use the PPoE password to verify service. The PPoE program could have been left on the main PC, there are some weird ones out there that run in the background etc.

Perhaps they had it set up right, but then did a hard reset of the Linksys, and forgot to put the PPoE back into the Linksys setup screen? And that's when it went down?

Also, the Sprint DSL modem is likely to be locked down, and only accessable by them. You could try calling their tech support and asking if they can force a reset of the modem, or if they can update it's firmware remotely.

I get these funky problems too with my broadband/Linksys setup, and I usualy just fix them by rebuilding the network from scratch, working backward step by step.

I have a smattering of "home LAN" clients too, and once I worked for hours on their router/cable modem setup. I finaly called tech support for the broadband provider, and it turns out they hadn't paid their bill. :rolleyes:
 
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IsaacHayes

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From what I've read online, they say not to run the modem in bridge and that it should work...

I can access the sprint modme by telneting to it and using the default password.

EDIT: Also, when reading the sprint how-to they say to un-install WinPoet. That's a PPOE app IIRC.
 
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ABTOMAT

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I can't add anything to this discussion, but I just got back from an entire day spent fussing with a new WRT54G V5 and a new Linksys USB NIC and feel like venting. A fraction of the time was sorting out the router, the rest was trying to work around half a dozen problems Linksys' software has with XP SP2. And the "one-button" security deal is bunk--as soon as the router gets power cycled there goes the settings. At least regular 128-bit WEP still works. I'm praying it's working again tomorrow so I can start getting ready for Christmas.

So much for progress. Four hours to get a new NIC working on a new computer, while my 1997 Toshiba 133MHz laptop connected instantly, runing 98se and using a five-year-old Netgear PCMCIA NIC.

I admit I'm not much of a wireless guy, but seriously. And this was after I told the client to _not_ to get Linksys--it's allergic to me.
 
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