User profile for user: Alan Shaw
Alan Shaw Author
User level: Level 1
25 points

Power Mac G5 ethernet stopped working

This is a long post, but please humor me! 🙂

Last Monday the built-in ethernet on my Power Mac G5, which has worked great since I bought it in February 2004, stopped working. In the Network preferences, I would get a message that the cable was plugged in but the Mac wasn't getting an IP address. I re-booted, checked the cables, swapped cables, re-set my router, re-set my cable modem, etc. I also checked the ethernet on another account and deleted the network preferences and ran the Hardware Check off my install discs. All to no effect. I know my Internet works because I'm writing this on an old PC that shares a connection with my Mac.

So I took it to my local Apple Specialist. He zapped the PRAM several times, booted it into Unix and re-set the Internet hardware. This did nothing. He couldn't get the ethernet to work. He said he felt a power surge fried the ethernet and to fix it would require replacing the logic board for $700. Instead of doing that he suggested getting a $30 PCI ethernet card and using it.

So I got a PCI card from him and installed it.

Now it gets weird.

The new card gives me the same error messages as the built-in ethernet plus a new one. The messages cycle quickly between the Mac seeing a cable plugged in but no IP address, and not even seeing the cable plugged it.

I called the shop back and they suggested re-installing Mac OS Panther using an archive install. I am in the process of backing up data before doing this and just wanted to see if anyone has had this problem and solved it without having to re-install the OS, something that makes me nervous.

Does this sound like a Mac OS problem?

Thank you in advance for your help!

Posted on Oct 31, 2005 11:32 AM

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User profile for user: Alan Shaw
Alan Shaw Author
User level: Level 1
25 points

Oct 31, 2005 12:45 PM in response to Alan Shaw

Update: I get an Internet connection (green light in Network Preferences) on the new card, but just for a few seconds at a time. It never holds for long. But I am able to connect to the router for the few seconds the connection holds.

This seems like a little progress, but not much. I can't get any connection through the built-in ethernet. I'm still planning on re-installing Mac OS 10.3.
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User profile for user: Tom Nelson1
Tom Nelson1
User level: Level 4
2,711 points

Oct 31, 2005 3:00 PM in response to Alan Shaw

If your internal Ethernet port is indeed bad, I'd suggest you disable the port in your Network preferences.

I don't have panther installed, but it shouldn't be to different from Tiger. In Tiger select System Preferences, Network. In the drop down menu labeled SHOW, select Network Port Configurations. Remove the check mark from any ports you are not using (Built-in Ethernet, Etc.). Click Apply now. You shouldn't have to, but for the heck of it, restart your Mac, and see if your PCI Ethernet connection is more stable.

Tom N.
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User profile for user: Tom Nelson1
Tom Nelson1
User level: Level 4
2,711 points

Nov 1, 2005 3:39 PM in response to Alan Shaw

Well it shouldn't have to much to do with your problem, but lets get this out of the way for completeness sake.

How is your Ethernet configured on your Mac? Is it DHCP or static IP? Is your Routers Ip entered into the DHCP and/or Static network window? And is your router and your Mac on the same subnet?

And just for the heck of it, what make/model of router and PCI card are you using?

As I said, this is mostly just to help others see if they have run into anything similar.

I have used a PCI (Asante 690) Ethernet card to replace a bad internal Ethernet port, just as you are. (this was on a Dual G4 Quicksilver). Actually it is still in use as one of our servers with the PCI Ethernet card still working fine and the internal network port disabled.

Tom N.
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User profile for user: Alan Shaw
Alan Shaw Author
User level: Level 1
25 points

Nov 1, 2005 11:17 PM in response to Tom Nelson1

Tom, thanks for all the help! I'm feeling a lot better about the situation. 🙂

I'm using DHCP to connect to my years-old D-Link DI-604 four-port router. My new ethernet card is a D-Link, too, though I don't remember the model number. I'll post that ASAP. I haven't entered my router's IP address info in Network Preferences.

I have some good news, though. I took the Mac back to my Apple Specialist and he plugged it in and was able to automatically connect to the Internet using the new card! He says this shows my computer isn't the problem. Perhaps my old router needs a firmware update?

However, before taking it in I had tried plugging the Mac right into my Terrayon cable modem from Comcast, bypassing the router. The Mac saw the connection but said I wasn't getting an IP address (a yellow "light" in Network Preferences). I think this means I need to fiddle with some settings (but I don't know which settings) or perhaps call Comcast? But shouldn't my card be able to draw an IP address right off the cable modem, like the router does?

I was thinking of just switching ethernet cables off the cable modem when I need to use each computer rather than messing with the router, assuming I can get the Internet to work straight from the cable modem to my Mac.

Do you know what IP address fiddling, if any, I need to do? Oh, Comcast says they supply one dynamic IP address per account, FYI.
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User profile for user: Tom Nelson1
Tom Nelson1
User level: Level 4
2,711 points

Nov 2, 2005 8:40 AM in response to Alan Shaw

You may not be getting an IP assigned from the modem because most cable companies lock the modem to a specific device. That is the modem is told it can only talk to device X. In your case device X is your router.

This locking is done via the MAC (not your Mac, but an Ethernet devices Media Access Control address). Every Ethernet device has one. When you originally connected your router to your modem, the modem learned the routers MAC address. When you plugged your G5 directly into the modem, the modem say that a new MAC address was connected and refused to allow service.

The MAC locking mechanism is trivial to get around, and in most cases you could call your cable service and tell them you change the device connected to the modem, and they would reset it.

However you can do the same thing, just power off you modem for a few minutes, say 5 minutes, then turn it back on, and the modem will grab the new Mac address of your G5 and lock itself to that.

Of course, when you go to put the router back in place, you will need to power off the modem again to get it to see the router.

One last point. When you power off the modem, your G5 could get confused by the loss of signal from the modem. This wont hurt anything, but you may need to restart your G5 before it sees the modem and makes a connection.

So if after your power cycle your modem, and your G5 hasn't pulled an IP, you can just restart your G5 and it should be OK (you can also achieve the same thing usually by unplugging the ethernet cable from the G5, and plugging it back in).

Good luck!

Tom N.
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Power Mac G5 ethernet stopped working

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