Can't Reach Modem's Diagnostic Page

I've got a Comcast issued (and labeled) Scientific Atlanta DPX2100 modem. It works fine.

I run FireFox and IE, with XPHome, fully patched. I have the modem's diagnostic page, http://192.168.100.1, as my home page in FireFox, so that I can easily check the SNR. Recently, I can no longer reach the diagnostic page. FireFox times out. I tried with IE, but the same thing happens, page cannot be displayed.

However, I can browse the web alright. I've rebooted many times.

Any ideas?

TIA

Reply to
Bruce
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Power down modem 30 seconds by your watch, power up. . . . ..

Reply to
Bit Twister

Bit Twister wrote in news: snipped-for-privacy@wb.home.invalid:

Damn! That did it.

Come to think of it, that's probably why I had to reboot my modem (and router) many, many times when adding new laptops to the home network. Guess I never hit that magic threshhold where a new config file is sent from Comcast.

Lesson learned. Many, many thanks.

Reply to
Bruce

*S*H*I*T* !!!!

I've been battling a similar issue on two different Comcast modems and this is probably my problem. I can't wait to check it out.

What the heck dose "30 seconds by your watch" do??? I did power down and up... but I'm sure I didn't wait a full 30 seconds.

Anybody?

-Frank

Reply to
Frankster

What you are after when trying to reset any electronic device is to remove power long enough for all capacitors to discharge. I think the helpdesk's documentation has the customer power down for a minute.

Reply to
Bit Twister

Do you know if possibly it would take this kind of discharge before the modem was capable of working with a different MAC address?

The reason I ask is this... new computer, modem assigns to the PC Private IP

192.186.100.10, Private Gateway 192.168.100.1, mask 255.255.255.0, public DNS (whatever). All looks good. But no Internet??? Of course, the MAC address is different than the previous computer. However, I accessed the config page at 192.168.100.1 and it showed that it picked up the new MAC address just fine. I dunno... I never did wait more than maybe 10 seconds during power down.

-Frank

Reply to
Frankster

You should always take the 30 second/longer when the downstream device mac has changed.

Hmmm, would have assumed cable modem would assign an internet ip address, not a lan ip to said mac.

Of course, the MAC

I have no knowledge of what the modems web page values mean at any given point in time. The page can indicate the mac visable on it's lan side but might not indicate the mac attached to the WAN connection.

The recommended procedure is, power off modem and device connected to it. Powerup modem, wait for steady state of leds, power up device which would do a dhcp client request for an ip assigment.

Different mac device connected to cable modem should get you a different WAN ip address. If you powercycle for one minute and still cannot get connectivity with new device but can get it with old device, then maybe, your ISP has married connectivity to a mac value. You would have to call them to change old mac for new mac and power boot again.

This assumes new device is able to manage the dhcp request correctly.

Reply to
Bit Twister

Well, it is requesting and receiving a 192.168.100.xxx series address from the modem.

Thank you. Appreciate the info. I will try the more elaborate power down sequence of all items in the chain.

Funny, I am still confused about whether the Comcast modem is supposed to hand out a public or private IP. So far, for me, the two modems I have had dealings with that are not working would hand out a private IP (i.e.

192.168.100.10). The only modem I have had experience with that was working properly handed out a public IP to the computer itself (single computer connected). So... beats me. I don't really care what IP it hands out. Just looking for where to start troubleshooting.

This is the first time I've messed with Comcast cable modems. But it sure seems strange that the power on sequence for all the devices is so critical (modem, router [if any], computer(s), etc.). What the hell happens after a power failure and restore? Do you have to go through all this manually again? I understand that the DHCP server has to be up before requesting an address, but...

One of my "problems" may be solved when the owner returns from his trip and I can try the power down for 1 minute sequence on it. At least his modem has all lights on (synched, I guess). The other one I'm having trouble with doesn't come up with all lights. Seems it might not be synced with Comcast. So... I suppose a phone call to Comcast is definitely in order there.

Unfortunately, I have not been able to devote adequate troubleshooting time to either of these cases. I keep having to leave the respective sites before I get a handle on it. Definitely not time to call Comcast, punch in a bunch of menu numbers, wait for a technician and go through all the expected troubleshooting steps. I'll get the time sooner or later. So far my involvement has been just hit and run.

-Frank

Reply to
Frankster

But that maybe the default when there is no connection to the WAN/headend equipment.

I would suggest it would give out a WAN side ip address. CableOne.net and Comcast.net modems give you a WAN ip address. Not a 192.168.x.x ip.

That I can beleive. It would be default so you could access the modem web page.

This powerup sequence is for when you change MAC devices. In your power outage example, you have a race condition, Usually the computer will be the last piece of equipment to to ask for ip, depending on operating system. If you were to watch for awhile, you will notice the public ip address does not change very often.

Now a power glich/brownout could leave the modem logic dinked up, which would require a good power reset.

Yep, no sync, no dhcp lease from the headend, and no connectivity to internet.

I'll do the power steps just like the tech would walk me through before placing the call. As soon as we get through the customer verification steps, I'll reel off each step preformed in the same order they would had me do it in the past. Helpdesk says, ok, let's move the problem up the chain. :)

Maybe a batch job/script to watch for outage and it grabs the signal data from the modem for checking later. Ping failure will tell you when you loose connectivity. You can use wget to fetch the modem web page.

I wrote a perl script to tell me about signal level and lease/ip changes on my Linux OS.

Reply to
Bit Twister

In article , Frankster wrote: : :Funny, I am still confused about whether the Comcast modem is supposed to :hand out a public or private IP. So far, for me, the two modems I have had :dealings with that are not working would hand out a private IP (i.e. :192.168.100.10). The only modem I have had experience with that was working :properly handed out a public IP to the computer itself (single computer :connected).

That's as it should be. When the modem has a connection upstream, then it gives out the public IP that it receives via DHCP from Comcast. If the modem has not been able to connect upstream, then it gives out a private IP (with a very short lease time) so that the connected PC will have _some_ IP address to work with.

Reply to
Robert Nichols

Thank you. That helps. Please bear with me... I had yet another terrible experience last night with another Comcast modem and a Netgear wireless router. (Intalling the Netgear for home lan - was single computer before). The Netgear Wan port was never able to pic up *any* IP from the Comcast. I verified this by going into the Netgear config and looking at the 0.0.0.0 Wan address. The attached computers (one wireless and one wire) were both getting 192.168.1.xxx assigned by the Netgear, but had no Internet connection (obviously).

I went through all the various recommend long power downs for the Comcast but still no-joy. To complicate matters, this particular Comcast modem had a battery backup built in. No on/off switch. After pulling the plug the damn lights stayed lit for a long time. Gradually dimming until off. Except... of all things, the power light never went off. Geeze, it's one thing after another! (LOL!)

So, I brought the Netgear back to my home (shop) to check it out. Plugged it into a "known good DHCP server" switch port on my network, and it works

*fine*! Picks up the wan IP right away. Dishes out an internal IP to connected clients and works for Internet connectivity. Virtually plug and play. Damn. Why the hell doesn't it work that way with the Comcast modem?

The only thing left I know to do is to leave the modem off for an hour or so (instead of merely 2-5 minutes).

BTW, I did call Comcast. As far as they were concerned there should be no MAC address issues. It should "just work".

-Frank

Reply to
Frankster

Hello!

Well, I finally got the bugger installed. The customer left his modem off all night. When I arrived everything went well. The Netgear got a public IP from the Comcast modem, it passed out private IPs to the clients and everything worked fine.

So.. what I learned from this (my first real experience with Comcast modems) was, first, to make sure you have an extended power off period. Second, check the status of the

-!*S*T*A*N*D*B*Y*!- SWITCH on the modem! Who the hell pushed THAT!!!! Who needs a stinkin' standby switch anyway! What the hell good is it!! LOL!

Thanks everyone for their input.

-Frank

Reply to
Frankster

...

Modems with a battery backup also have a "Reset" button. Press and hold for 30 seconds.

Reply to
Robert Nichols

Well, it is useful for when you want to disable the internet connection and leave the hardware powered up.

Reply to
Bit Twister

That it does. Yep, that it does. :)

-Frank

Reply to
Frankster

Next time I'll look harder for that. Didn't see it. Wouldn't have known to hold for 30 seconds anyway :) Thankfully I did finally succeed. Just lost a little (more) hair, and ego... that's all! :)

Thank you.

-Frank

Reply to
Frankster

"Frankster" wrote in news:OOWdnabHGNhA9HnZnZ2dnUVZ snipped-for-privacy@giganews.com:

Well, I have a Motorola SBV5220 Voice-over-IP (VoIP) cable modem, and while it does have a Standby button on the top, there is no reset button. However, there is a small hole in the back that is marked REBOOT. One would have to take a bent paperclip to reset it. I've just always unplugged the power for a minute or so on other modems I've had, and never had to reset this one. Now, at least after looking, I know it can be reset.

Reply to
John Gray

Bit Twister wrote in news: snipped-for-privacy@wb.home.invalid:

I have a Motorola SBV5220 Voice-over-IP (VoIP) cable modem and the Standby switch allows me to disable the Internet to the NAT router and still use the phones.

Reply to
John Gray

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