Hey all,

First off, thanks for reading and any help you might be able to offer! I probably should have posted in the Network forum, but there's not many people there.

Here's the problem:
I just moved and got AT&T DSL hooked up. They sent me a Siemens Speedstream 4100 modem. I have a Linksys BEFSR41 router (wired only, 4 port ethernet).

Now I can't get the router to recognize the modem. On the front of the router are LEDs for each ethernet port and the WAN port. The LINK LED just won't light up no matter what I try - which signals that the router won't recognize the modem. The modem recognizes that the other end is plugged in (via the Ethernet LED).

The thing is that the 4100 modem has the PPPoE authentication on it, which works fine. I can hook the modem directly to my computer and everything works fine. So it must be the router-modem connection.

I've tried:
Having the router get an IP automatically from the modem.
Changing the router's IP address.
Having the modem pass PPPoE authentication to the router.
Bridging the modem.
Power cycling the guts out of everything.
No matter what I do, it never lights up the LINK LED. Its driving me nuts! I'm hoping someone's experienced a similar issue and can help me out?

Plug the modem ethernet cable into the WAN port on the router. Go into the router and configure PPoE with username and password. Set up a LAN connection to the router on your computer. Make sure that your firewall is not blocking the router internet connection.
If the port is not lighting up, it may be a dead port.

Thanks, I did try that, but to no avail.
I don't think its dead, it just may be that the router is too old for the PPPoE on the modem configuration. :-(

That's the only thing I can figure that went wrong. Course, it could be dead, but i'm too lazy to find out. I ended up just getting another wireless router since i'll need it for my wii anyways.

Thanks for the help!

with the modem handling the PPPoE authentication, set the router up for standard cable modem. (basically a hardware reset on router will set that up). then change anything regarding firewall and such on the router.

yeah I tried setting up the router to accept an automatic IP address from the modem (which should happen w/ PPPoE on the modem), but it still didn't work. Maybe evongugg is right w/ the dead port/router idea. :? Its all good now since I got a new router.

Had the same problem with my D-Link 624 Rev C. Here is what I've done so far:

1) disconnect router and plug directly into the DSL modem
2) get into the DSL modem webpage (same as wireless router)
3) switch to "always on"
4) copy tech info (primary DNS and secondary DNS)
4) reconnect wireless router
5) make the connection to Cable Model
6) input the two DNS addresses

This should do it.

Let me know how you make out.

I have the same issue with my WRT54GS. Recently I got DSL and I'm trying to hook up my Siemens 4100B modem to my Linksys WRT54GS, but so far I'm having zero luck. Running directly off the modem works fine, but the minute I bring the router into the equation everything goes south. I have configured the mode/router as follow:

1. configured the modem to bridged.
2. plug in model to WAN port on router.
3. configured router to run in PPOE mode.

No luck, I know the router is port is good because It works with Cable modem.

Try changing the IP address of the router. Linksys defaults this to 192.128.0.1. I'd change it to something different, like 10.0.0.1. The modem (as far as I can tell) is hardcoded to take 192.128.0.1. This causes a bad conflict.

Leave the authentication (PPPoE) on the modem, and set the router to get an IP address automatically.

On my old router, I couldn't change the entire IP address, just the last number.

My solution was to get a new router.

Have you tried a crossover cable? If you're not getting a link light, messing with the IP settings will get you nowhere.

EDIT: Replying to the OP. Goofy "Post Reply" button is randomly replying my posts to various folks.

With DSL in my area and every router hookup, I've gone in (192.168.x.x) and set them to cable modem (like a straight pass thru). Seems PPOE on the router messes with the DSL. Then set the router to DHCP & automatically assign addresses.
And don't forget to rename the login and password to the router, and wireless SSID and WPA password asap! 3 idiots in my area have linksyses wide open with default factory passwords.

I did try the crossover at the begining. Thanks.

Actually the modem's default IP is 192.168.0.1 and the router is 192.168.1.1

Also, the version of the firmware I'm using is 4.71. Is anyone using this version with the PPOE configuration?

Connect your PC to the router and clone its MAC address onto the router. I'm not sure that matters with no link LED showing, but it might if the modem has been set to only allow a specific MAC to connect to it.
Then plug the router into the modem and see if it flies.

Oh yeah sorry about that, but my suggestion still stands. I think it could be related to the subnet mask on the modem as well.

I highly doubt that the modem is configured to allow only 1 MAC address. That would be a nightmare for consumers and ATT.

Also, remember when you do a IP change, do a ipconfig /release and a ipconfig /renew to get your new IP address from the router.

How my netgear is set up is I have PPPoE on the modem and the modem is set to always provide the connection to the router with a specific address (192.168.64.1? - from my months old memory).
The netgear is 10.0.0.1 and to automatically get the IP address from the router (akin to how a cable router is set up). Then DHCP is handled by the router to my computers.

Another note, you can try to disable as much as security as you can on the router until you get it to work. After I make it work and I've got the correct settings up and going, then I reenable my security.

I hope this helps. I have a linksys befsr81 with the 4100b modem with AT&T and I was having problems.
I found this page
http://www.dslreports.com/forum/remark,15694046
with detailed instructions on how to setup the modem and router. I performed the steps exactly and they worked for me.
If it still doesn't work, then plug directly into your modem and try to connect that way. If you can connect through the modem directly and the instructions don't work for configuring it, then it could be the router.

Good Luck

Just out of curiosity since you moved, and now have I assume a different modem, did you reset the router to its default settings, using the reset switch?

1. IP address is completely irrelevant to an ethernet connection
2. IP address is completely irrelevant to an ethernet connection
3. PPPoE is completely irrelevant to the ethernet connection
4. ...all of the higher level protocols are irrelevant to the ethernet connection, all of the DSL negotiation is irrelevant to the ethernet connection between the router and the DSL modem
5. ok, we'll rule that out
6. Is there anything that *does* cause the link LED to light up?

I *think* I have the same router (it's at home and I don't recall the model number exactly) so I'll try to give some model-specific instructions below. If they aren't quite right just try to adapt them.

My best guess: crossover. There should be a button for it on the router for the "WAN" port but you have an older router and it doesn't do auto crossover detection. Try a different ethernet cable. Try different ports on the router. Try both settings for the manual uplink crossover button (little square black button on the back). If your WAN port is broken just get a crossover cable and use one of the regular ports.

The ethernet connection has to be established first before any other levels of communication can happen so don't even worry about anything else until that link light turns on. When you hook your computer to the router does the link status light turn on? Does the computer get an IP address?

That link status LED is a physical layer ethernet link up indicator. None of that other stuff matters until the ethernet link is up. I assume that you at least tried to use the connection even though the LED didn't light up (the LED could be broken)?

To all the people who suggested tweaking firewall, authentication, and IP settings when he clearly stated that the physical layer ethernet link up status indicator wasn't turning on: don't give out advice if you don't know what you're talking about.

Nobly, if you ever do manage to figure out what was wrong with it we would all appreciate some feedback. Did the hardware goblins really break your router during your move or did you just need to push the crossover button? Inquiring minds want to know.

Oh yeah. Multiple times. And then another one for the heck of it.

Flasher, you have revived my technical curiosity in it. I had solved the issue by just getting a new router because I realized I would need wireless anyways. But I will contemplate some extra investigation this weekend and see what happens.

I know the modem works fine because the modem's ethernet LED would light up is if I bypassed the old router and went straight to my computer. I'm relatively sure that the router is ok - it was when I decommissioned it. I know the switch part works, it was just the WAN LINK port that would not recognize the modem.
The router does have auto-detect crossover or straight (at least according to the data sheet). That was one of the first things I thought of and double checked. I've tried different cables. Did not think about trying a port on the switch though - i'll have to give that a shot to see if the physical layers will recognize each other.

Router to computer is fine. I have an IP from the router's DHCP and can ping, etc. Its seriuosly just the path between the router and modem. And since I've verified the modem works, its down to the router.

So pretty much I figured the WAN port was either fried or dead and just got a new router since I had to to go wireless anywho.

Oh another thing I just remembered - the modem's Ethernet LED would light up when I plugged it into the router, but the router's would NOT. That was what confused me - it seemed like the modem knew the router was physically there, but the router was refusing the acknowledgment or something. That's why I pursued the upper layer protocol methods.

I like the goblin theory... Thanks for the ideas, I'll post back next week. If you have more ideas, love to hear them.