Apple Airport Extreme Base Station

[bryanall]

Would greatly appreciate some thoughts on following.

Something is changing my Network settings on a G5 Mac Pro.
Set up is:
Belkin 4 Port modem / router.
LAN 1: running Mac Pro G5 with Leopard 10.5 installed.
LAN 2 running Desktop Mac G4,
LAN 3 running Apple Extreme Base Station for Powerbook G4 with Tiger installed.

Switch on Belkin modem.
Desktop G4 and Powerbook connect immediately to the Internet when booted up, no problems.
G5 won't connect.
If I open System Preferences on the G5, go to Network it shows all active and connected. If I go to diagnostics, or Set up assistant and follow the prompts, it ends up saying they cannot fix the problem.
Belkin modem has all correct lights on, and steady.

This morning I switched on the Belkin, booted up the desktop G4 and immediately it went online. I then booted the Mac Pro G5 and that immediately went online OK. Later I shut down the G5 and after a couple of hours booted up again.
The G5 was not connected to the Internet, and the settings had changed. I use Safari for my Browser. I get the same result if I use Netscape 9, or Firefox.

Correct settings on the G5 are:
Automatic DHCP
IP address: 10.1.1.2
Subnet Mask: 255.255.255.0
Router: 10.1.1.1

They change themselves to:
Automatic DHCP
IP address: 10.0.1.2
Subnet Mask: sometimes changes to 255.0.0.0
Modem: 10.0.1.1
If I enter the correct settings Manually quite often they have changed back to the incorrect settings before I can quit System Preferences, even if I click the padlock.

It appears the Apple Airport Extreme Base Station is overriding the settings on the G5, if I disconnect the Base Station from the Belkin the desktop G4, and the G5 have no problems. bva

 

[Makosuke]

When you say that the correct values change immediately if you set them manually, does that manual setting include DHCP set to Automatic? Because if so, that much is normal--if the Mac is getting its network info from DHCP that will by definition override anything else you set.

If you switch it to "Manually" (rather than DHCP), apply, and it still changes whatever you manually configure, then that means the issue is something on your Mac either changing the settings on its own (there are, I think, 3rd party tools that might do this, though I've never seen one personally).

If that's not the case, then it sounds an awful lot like the G5 is seeing two different, and conflicting, DHCP servers. Were that the case, I believe it would pull settings from whichever it got to first, which could explain the symptoms you're describing.

The first thing to check would be to make sure that the AEBS is connected to the Belkin router via its WAN port, not the LAN port(s). Having it on the LAN port would, I'm pretty sure, result in having two DHCP servers and all kinds of potential weirdness. Checking whether the AEBS is set to give out addresses in the 10.0.1.x block would confirm that that's where it's coming from.

Also: What specific model AEBS is it? I can think of at least four different products with that name--old UFO style, newer 100MBit 4-port, even newer gigabit 4-port, or the newest dual one? Probably doesn't make any difference, but it won't hurt to know.

Another thing to check would be whether you are using any reserved DHCP entries, or if you're letting the router(s) handle all that; could be that the AEBS has a reserved entry for the G5 but nothing else, and so it's the only one its arguing with the Belkin over.

Oh, and does the G5 also have an Airport card, or just a hardwired connection? That's another one that could cause oddities.

That's a few things to try and see if it helps. Another option would be to do a factory reset of both routers and reconfigure them again; if there's something weird set from earlier that you'd forgotten about or weren't aware of, that might fix it.

 

[bryanall]

Aebs

Hi Makosuke,
I think you have scored a hole in one !!!!! On your advice I checked that the AEBS was connected to the Belkin router via its WAN port, not the LAN port(s) and found it was connected to the LAN port. I changed it to the WAN port.
I then shut down the G5.

I booted up the G4 Powerbook, and connected immediately to the web via the AEBS.

Then booted up the G5, and it connected immediately to the web via the Belkin.

Booted up the Desktop G4 and also connected to the web OK via the Belkin.

This problem has been driving me nuts over the last week or so, and it now looks as though all is well. I really do appreciate your expert advice.

With thanks and regards, Bryan

 

[Makosuke]

Glad that helped. Actually, particularly glad in this case because that was by far the most obvious possibility, and it'd probably be much harder to track down the cause if that wasn't it.

I'm also a little surprised that the network was working as well as it was with that setup; it could easily have screwed up the other connected computers as well.

 

[bryanall]

Aebs

Hi Makosuke,
When you say you are surprised the network was working as well as it was with that set up, I have been using the LAN port on the AEBS for the past 2 years at least, from when I bought the AEBS.

Before purchasing the BELKIN I was using a 4 port NETCOMM modem, again I was using the LAN port on the AEBS, and after a while I was having a similar problem. With my limited knowledge I presumed it was the modem, and purchased the BELKIN. After connecting up, problem solved, until the last week or so then it began playing up. Anyway, thanks to your advice everything running smoothly. With regards, Bryan