3 routers and 2 modems later and I still can't pull a WAN IP on any router

likwidneo

Junior Member
Jan 1, 2010
10
0
61
so yesterday i got a bunch of new furniture and decided to reorganize my room to accomodate it all. I have 2 machines in here, both built with my own 2 loving hands running windows 7 ultimate 64, my main rig, and a file server. Up until now I had been using an old beater of a linksys 54g router that's still truckin after god knows how many years. the connection had been working just fine since at least... october? and this has never happened before.

my ISP is Comcast and I forget what my plan with them is, but its the highest grade in my area, i pull a little over 35mb down on speedtest.net. so after i reorganized everything and plugged it all back in, now the router will not pull an external IP address from the modem.

networking is working just fine, i can pull files from my file server no problem, but no internet. tried renewing the IP address til its blue in the face, nothing. hard reset and power cycled everything multiple times. nothing. if i plug the modem directly into my main rig and power cycle it, all of a sudden internet works just fine, and ipconfig successfully pulls an external IP address. so at first i thought my router finally died after 7+ years of loyal and faithful service. i went to best buy and got a new linksys E1200.

came back home, configured the sucker, plugged it in, no dice again. now mind you my comcast modem is made by cisco just like the router, so there definitely should not be any compatibility issues i would think. so i went today to comcast, got the modem changed out, brought the new one home. STILL NOTHING. again internet works just fine with a straight connection, but the router absolutely will not pull an external IP address. I can walk away from it, wait half an hour, try to renew it later, doesn't matter. I tried cloning my PC's mac address, nothing.

Went BACK to best buy, exchanged the new router for the same modem, came back home, and well here i am. ive been through 3 different comcast support reps, and well they're about as useful as taping sandpaper to your palms while watching porn. and they want to charge me $50 to send a tech out to my house, or try to sell me some BS call center remote tech support service (which I do for a living, btw) just so that they can sit there and refuse to admit to me that they're having an issue which at this point i'm 99.999% sure is on their end.

So my tech guru kung fu is good, maybe even great, but not spectacular. If I had to guess there's a glitch on their end that is blocking certain hardware profiles from accessing the network on my account and that data never got updated on the modem(s) until i last powercycled it right before I reorganized the room. I could probably get this resolved by getting a new account or convincing these morons to flush my account data from their network servers. I also may be a victim of the new 6 strikes policy and I don't even know it yet, although from what I've heard, 6 strikes just throttles your bandwidth, it doesn't nerf your router. And even if it was 6 strikes, that would be amazingly fast. I'm not even sure if I've actually even been able to do enough downloads to get the 6 strikes in yet since they implemented the policy. But even their reps had no idea what i was talking about when i mentioned 6 strikes, so... buh?

I'm going to try and get a gateway from them on Friday (which i despise gateways sorely, but I'm running out of idea's and they're not very helpful) and see if that helps, but at this point they're being very resistant on helping me any further without charging me any money only to (i suspect) keep telling me the problem is with ALL THREE OF MY ROUTERS.

So, beyond that, if anyone has any useful idea's on what I can do about this issue, I would greatly appreciate some help here.
 

serpretetsky

Senior member
Jan 7, 2012
642
26
101
You said you power cycled and you tried copying the mac address, so I dont think this will offer you anything, but either way, you can give it a try.

You said you power cycled the modem, but just to be sure:
1) Connect everything the way you want it and power it all on.
2) Disconnect the power from the cable modem and keep it unplugged for about 5 minutes. If you get phone service through comcast you may have to locate the backup battery in the modem and remove that for 5 minutes as well.
3) After waiting for 5 minutes with the modem completely powered off, reconnect it. Let it boot it up.
4) If you're internet still doesn't work, try to do a simple quick power cycle of your router and modem one last time after that procedure.

good luck.
 

likwidneo

Junior Member
Jan 1, 2010
10
0
61
cables aren't it. i've used 3 different ones, and once again the cables will all work perfectly going from the modem to the machine, but the routers cant pull an IP address.

i've waited over 10 minutes to reboot stuff in between power cycles already, no dice.
 

ch33zw1z

Lifer
Nov 4, 2004
38,807
19,393
146
What kind of modem are they giving you? Model?

Interested in trying out your own modem? I use a Motorla SB6120, it's supported on their site..

edit: When you power cycle your modem, you will need to disconnect the coax as well.
 

Bricked

Member
Mar 8, 2013
27
0
0
Have you power cycled the modem with the router connected to it?

At least some models of Comcast modems associate with the MAC address of the first device to connect to it when it powers on, and won't work with any other MAC address. To associate with a new MAC address, you'd need to power cycle the modem and then connect the device you intend to use or have it already connected. MAC cloning is theoretically supposed to take care of this, but I've found that power cycling works best. You've mentioned that you've power cycled the modem with the PC directly connected; it's not clear whether or not you've done so with the router connected. If you have not, then it's worth a try.

In any case, Comcast does suck but if you have internet when connected directly to the modem then the issue exists either on your side of the modem or within the modem itself. Replacing the hardware multiple times pretty much rules out any hardware faults; the only thing I can think of would be the MAC address association.
 

likwidneo

Junior Member
Jan 1, 2010
10
0
61
don't know the exact models and i'm at work right now. first modem was a cisco, and again these are linksys routers, 2nd modem was an ubee. if i have to chose between using my own modem and using their gateway i'd rather just get their stuff and be done with it all. ill try the power cycle with the coax off again, but i know i tried that once already. i just got a call from comcast this morning saying they had completed maintenance in my area, maintenance which was supposed to be completed before i got home with my 2nd modem yeserday, but we'll see if that had anything to do with it.
 

Cabletek

Member
Sep 30, 2011
176
0
0
It is not possible for the maintenance outside to grant you a connection on the main computer and not the router. It will either kill the modems link to the cmts or not.

So if you can get a computer to see the internet consistently and not the rest, its your network. Most common reasons for what you are seeing:

Customer plugged modem Ethernet into lan port on router, no worky this way.

Customer did not power cycle modem then power up router after modem is locked online [there is an online light it should be solid and not blinking when its ready to bring up the router, so should the DS and US lights as well] and has picky router that only request dhcp data once then gives up, old 54g, notorious for this, hated those damn things, glad they are gone. Ig modem gets rebooted for maintenance they go dead require power cycle, hated those things.

In a few cases, customer confused power supplies and switched modem and routers, router not happy with missing voltage/amperage. No worky worky.
 

Fardringle

Diamond Member
Oct 23, 2000
9,200
765
126
Unplug power from both the router and the modem. Disconnect the coax cable from the modem. Let everything sit unplugged for several minutes (local techs here recommend at least 5 minutes, some places have said as much as 30). Plug the power and coax back into the modem. Wait until all link lights are lit up and not blinking, then plug the power back into the router.
 

likwidneo

Junior Member
Jan 1, 2010
10
0
61
still at it. still not working. ive upgraded the firmware to the router, i've tried at least 5 different cables. i have 2 routers. i've bridged the 2 routers into each other putting each on both ends. both can receive an IP from each other. went to comcast and changed out the modem a 3rd time. brought it home and hooked it up to the router WITHOUT plugging it into the coax first just to see if it could pull the routers internal IP from it before hooking it up to the coax. it couldn't. STILL no dice. i'm at my wits end. i've tried 3 different outlets in my room including the one that all this stuff used to work on. the plug on this router is physically incompatible with the new modem, so there is no way at this point i'm even getting my plugs crossed. checked the output on the plug, it matches the required input on the router.... I'm at my wits end here... something is really really wrong...
 

likwidneo

Junior Member
Jan 1, 2010
10
0
61
Modem is not going to LAN. I have been a computer technician for 16+ years. I would know very quickly if i made the mistake of putting the modem going to LAN...
 

AnonymouseUser

Diamond Member
May 14, 2003
9,943
107
106
No offense intended. At this point we have to cover all the bases. I'm 99% sure it's not a Comcast problem, though. That's not to say you don't know what you are doing, but it's easy sometimes to overlook the obvious.
 

likwidneo

Junior Member
Jan 1, 2010
10
0
61
i agree. at first i swore up and down that it was a comcast problem. but now after testing the new modem without plugging in the coax, it's a safe bet that they're not pushing any kind of bugged out firmware updates that are causing this to happen. at this point i honestly do not know. my only 2 thoughts left are A: some kind of obscure virus that targets cisco routers, or B: I've got 3 bugged out routers back to back to back, I don't know which one is more of an oddball longshot...
 

AnonymouseUser

Diamond Member
May 14, 2003
9,943
107
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Configure one of the routers as Static IP using the settings given to the PC and the PC's MAC address. Disconnect the PC from the modem and plug the router into the modem. The router should work. If it does, reconfigure the router as DHCP and reboot both the modem and router to see if DHCP works.
 

JackMDS

Elite Member
Super Moderator
Oct 25, 1999
29,517
409
126
All ISP do the same "Silly" song and dance, they pretend that their computer at the service room can see every thing on the Network.

In reality it can see very little about specific client connection.

The trick is to go one time with their ritual of "song and dance" (connect disconnect do some voodoo dance etc.), then demand that a technician will come with his connection checker instrument and make sure that a valid signal comes out of the Cleint side of the Modem.

It is important Not to start arguing with the customer service person and claim I did this already. When on the phone with them either do again what they want, or if you know well your network pretend that you follow their instructions and nothing happens.

The ISP service is Not manned by the CEO, the low level employees have strict orders and they do not want to lose their Job because of the company's inadequate service protocol. The people on the phone did not establish service policies and do not have much say about it, they just follow on screen protocol.


:cool:
 
Last edited:

avos

Member
Jan 21, 2013
74
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0
Well I know for Charter they will block a device if there are more that 5 dhcp requests in a 3 minute time span. Tomato and Asus-wrt finally added some delay in their firmware for dhcp requests. I'm not sure if Comcast has the same policy. Generally the cause is the upstream connecting before the downstream and multiple dhcp requests being sent before any response is received. At this point the device is blacklisted, but doesn't realize it so it continues to send dhcp requests which keeps it blacklisted.

If this is indeed what is happening, your best bet is to connect with a pc and then set the router up to statically use the address/netmask/gateway that the pc received. Once connected you should be able to turn dhcp back on for the router. If you are going to do this you should also clone the pc's MAC to the routers WAN.
 

AnonymouseUser

Diamond Member
May 14, 2003
9,943
107
106
Well I know for Charter they will block a device if there are more that 5 dhcp requests in a 3 minute time span. Tomato and Asus-wrt finally added some delay in their firmware for dhcp requests. I'm not sure if Comcast has the same policy. Generally the cause is the upstream connecting before the downstream and multiple dhcp requests being sent before any response is received. At this point the device is blacklisted, but doesn't realize it so it continues to send dhcp requests which keeps it blacklisted.

If this is indeed what is happening, your best bet is to connect with a pc and then set the router up to statically use the address/netmask/gateway that the pc received. Once connected you should be able to turn dhcp back on for the router. If you are going to do this you should also clone the pc's MAC to the routers WAN.

You pretty much suggested the same as I did (Static > DHCP), but if Comcast is indeed blacklisting his routers, shouldn't someone at Comcast have told him?
 

avos

Member
Jan 21, 2013
74
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You pretty much suggested the same as I did (Static > DHCP), but if Comcast is indeed blacklisting his routers, shouldn't someone at Comcast have told him?

That would assume that the person you get from support actually knows how the underlying network works. I'm lucky enough to have a fairly knowledgeable Charter rep through work to talk to. I have a feeling if I called the residential support I never would have gotten any further than "Please unplug your router and modem for 5 minutes and try again."

Ironically it is that exact situation that was causing my issue previously (before switching to the latest asus-wrt merlin firmware) as when I plugged them back in together the router would start up far before the modem would completely initialize and start sending the dhcp requests.

At least in Charters case the blacklist only lasts for 3 minutes if no other dhcp request is sent, so blacklist might not be the right word. Short-term ban might be better. But if the device never stops asking for an address it can go on indefinitely.
 

AnonymouseUser

Diamond Member
May 14, 2003
9,943
107
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So how does this ban work when after the PC works you configure the router with the PCs MAC address? Wouldn't the blacklist/tempban be based on the MAC address?

I'm not saying you're wrong, I'm just trying to figure out how this would work in this situation.
 

likwidneo

Junior Member
Jan 1, 2010
10
0
61
well the static IP tip worked out. but the modem is still showing an error light as if nothing was going through. It's not even blinking to show data transmission...