Comcast has been spotty for me lately, and today it went out for a half hour on me, costing me about $400. Gotta get off my ass and get tether working on the phone.

Called them while it was out, got all their bs troubleshooting nonsense. The tech support guy is saying that he could talk to my modem the whole time though, so the issue must be with the modem (since all the computers went down at the same time couldnt be the computers or the cabling, and I was connected directly to the modem during troubleshooting bypassing the router).

I think thats bullshit, he's just blaming the modem since its not their equipment. Its been a long ass time since I did any networking [censored] though, is there another explanation besides a bad modem for comcast to be able to talk to the modem and get info back from it, but my computer cant get connectivity? Was not getting a valid IP address after ipconfig release/renew, renew would just hang.

Just started working after about 15 minutes on the phone with him.

Their DHCP server could have been down and he could have just been script reading to you without actually doing any troubleshooting. One way to be sure they are not bsing is to power off your modem and see if they notice anything while they 'talking' to the modem. It is possible that signal to the modem may be weak also which could cause an incident like this.

Tarkus

Some [censored] from their end the tech probably didn't know about.

dns issues might make it look down as well.

I switched over to using OpenDNS a while back and have been happy with their free services.

Tarkus

Their phone system bounces your modem when you select "dont have service" now. Kind of irritating (what if you hit the wrong button on your phone), but the orange lights did come on the modem then.

So that kind of rules out dhcp issues right? The modem was apparently able to get an ip from them after rebooting.

DNS, some sort of routing/authentication issue or weak signal?

Do you get a public IP when you do a ipconfig /renew or a private one? Curious if you have a plain DSL modem or a router that does NAT.

If it is like 192.168.x.x then it is private and indicates some problem between you and the modem if you can't get that address, regardless of the public IP your modem gets.

They can talk to the hardware address of the modem. During the modem boot process the modem obtains an IP address and other parameters based upon the modems hardware address. This is the eight hex digits separated by : that you may be asked for sometimes that is usually on a sticker on the modem. If they reset the modem on their end and everything then worked then the problem was somewhere from the modem back.

The DHCP address you get has to be renewed, usually every 24 hours. If their DHCP server does not reply you could possibly lose your connection. One way that people hacked their cable modem in the past was to set up their own DHCP servers and set the modem up to obtain their info their instead of the companies servers. This was done usually to increase their speed. It took a while for the cable companies to overcome this hack.

DNS is Domain Name Services and is responsible for mapping IP addresses to names. You provider sets it up that your system gets the addresses of the name servers as part of the information it gets from the DHCP servers. Occasionally problems happen with their DNS servers and you can usually tell this is you know the IP address of a site and set that address in the browser instead of the name of a site you are trying to reach and can get to it that way.


Tarkus

The Time Warner / Roadrunner DNS servers flake out occasionally and it does seem like the connection is down, just like Adam and Tarkus say. I sometimes use our office DNS server when this occurs.

-- Johnie

eh, if he's not getting a dhcp address with ipconfig /renew it's a dhcp issue somewhere, either from modem/router to him, or from provider to modem/router.

When i was connected to my router, i had no trouble getting the 192.168.x.x address. When I connected directly to the modem, that was when /renew hung, and then finally got a comcast IP, think 68.something.

Cool, so if you get a public IP from your modem it's just acting as a standard network bridge. Even though they can "bounce" it remotely and you'll see the lights change thats just letting you know the status of the link layer, doesn't mean it/you have an IP address, as indicated by your failure to ipconfig /renew.

I'm sure you tried this but honestly I would turn it(modem AND router) off for a good minute then power it back on as my first step. You could be creating new problems by moving the connection from your router to your PC directly and obscuring the original problem which very well could have been DNS or something of that nature. Pretty much ignore the idiots that tell you to do that if you know your router is good and has not been changed recently.

Most bridges have a mac address timeout value associated with each ethernet port and it might have been expecting your router to still be connected which is why your PC couldn't get an address. After a certain amount of time that mac table cache got cleared and you were able to get a new IP.

I agree.DNS issues might make it look down as well. I still like DNS.

ya know what you need to do...yep you guessed it

REFORMAT

The option of last resort. Formatting & Reinstalling.
Gotta love it.