[malvarru]

I have cable internet through comcast (the only choice where I live, NJ). Actually, I should say I had cable internet. About two weeks ago the service was down. My computer (g4) stopped getting ip addresses from the server, and was assigning its own (by default: 169.xxx.xxx.xx). Several calls to customer service confirmed that the modem was working fine. I called a Mac service repair technician to come and take a look at my machine. 269 dollars and an upgrade to Os X.2 later, I still had the same problem. I took the computer to the nearest mac store and it was working fine there (getting the right ip, etc). Finally the cable company sends a technician of their own. The man, upon seing that I had a mac said: "I can not do anything. This has been a common problem with macs in the last two weeks. They suddenly become unable to get ip addresses from the server".

Needless is to say, I tried all the usual: unplugging the cable modem, rebooting the computer, changing the network preferences...

Is anybody else out there with the same problem? Does anyone know what is the problem and, perhaps, how could I fix it (since the comcast people can't?)

Thanks. At this point any help would be greatly appreciated.

[ghporter]

At this point I would advise you to make sure they know that you're not paying for service you're not receiving.

Once you've done that, look into buying a gateway router. They're useful little boxes sometimes, and they aren't too expensive, either. You can get one for less than $50 if you look around. Why do this? The DHCP client in a gateway router is not a Mac DHCP client. That means that whatever way Comcast's hosed up their DHCP server so Macs don't get IPs, it will probably not affect you.

I have two more things for you to consider. Many, if not most of the common gateway routers provide the capability to "clone" the MAC, or hardware address of your network card. Once you've set up and gotten running with this kind of router, you can do a litle experiment. Clone your Mac's address into the router and see if you experience the same problem you're having now. If so, that tells you a lot about what Comcast is doing: they're probably blocking Apple MAC addresses, probably in an effort to block AirPort users. If that is true, you'll need to clone a different address in your router, because sure as shootin' Comcast will eventually get around to blocking other network hardware.

<pant, pant, pant> Ok, I've finished my rant. Yes, I have problems with service providers cheating on what service they'll provide. Is there a problem with that?

[aaanorton]

Originally posted by GHPorter:
<pant, pant, pant> Ok, I've finished my rant. Yes, I have problems with service providers cheating on what service they'll provide. Is there a problem with that?

Heh. Typically, GHPorter has posted this sentiment BEFORE I could, in your other thread.
Needless to say, I agree with this assessment 100%.

[MichiganRich]

Hey Malvarru-

I had what might be a similar problem with my cable modem service here in Michigan. It was working fine for the longest time, and then stopped dead one day. My Mac also wouldn't get a valid IP address through DHCP, instead getting one of those 169.x.x.x values. To make it worse, everything checked out okay from the Cable company's end. Modem working, all the lights on and steady. In the course of troubleshooting the TCP/IP connection I saw that one little number had changed. That was the day I learned a (precious) little about something called "subnet masking", from reading about 30 pages of documents I pulled from the Apple Technical Support site. In the TCIP/IP panel there's the subnet mask field in there, and usually it gets a value of 255.255.255.0. Or at least its that way on 99% of the ethernet configurations I've seen, which admittedly arent that many. My cable company changed this to a value of 255.255.252.0, which is when my problems started. Apparently, from what little I can comprehend from the reading I did in the Apple Tech forum, this subnet masking technique allows the ISP to assign more IP addresses on the same Ethernet network. 255.255.255.0 gives them a fixed number of addresses that can be assigned, and then they start going to 255.255.254.0, 255.255.253.0, and so on... expanding the number of IP addresses that can be assigned on a given network. From what I can gather, Macintoshes do not like this subnet mask value changed from 255.255.255.0, at least not if they're getting IPs through DHCP. I jumped to this conclusion because using an inexpensive, plain-old Netgear RP-114 four-port Cable Router between computer and modem made everything work again. I cloned the Macintosh's MAC address into the setup of the router, and set the router to DHCP using the same info as before from my ISP. It worked, and has been working great ever since. Lord knows why, and I've never heard any evidence that the Macs dont like this "subnet masking", but from my personal experience (and the experience of a Mac-owning friend across town, also on Cable), they dont.
A side benefit is the NAT firewall in the router, so my computer isn't 'directly' hooked to the 'net. Locks only keep the honest people out, though, right? E-mail me if youd like to talk about the whole thing....

p.s.- If any network experts are around and can shed some light on this issue, or shoot holes in my whole explanation, please please feel free. On the other hand, if there are any 16 year old MacAddict forum rejects lingering around, please shut the f#@k up, nobody needs to hear your guesses and conjecture. Go learn something.

[ghporter]

MichiganRich has a great point. It wouldn't hurt to check your Mac's settings to make sure the netmask still is 255.255.255.0. If not, and changing it back fixes it, then you're way ahead of the game.

[malvarru]

Wow! lots of information between this and the other posting (I originally posted it on the g4 forumby mistake). I am going to try, both, the router and the subnet mask. I'll keep you posted with the results. If this is all happening because comcast is afraid I might be 'cheating' with an air port, they are going to hear me.

This website is a great source of information. I whish I had discovered earlier. Thank you all!