Help with network settings for Airport Extreme and iMac

[BobBob]

Hi there,



I don't know the first thing about Macs or about networking but I'm hoping for some feedback about my network settings. I have an iMac and have set up an Airport Extreme which is connected to a cable ADSL modem with a LAN cable. I've been fooling around with the settings and have screwed things up but I'm hoping if I get the numbers in the correct boxes it should be an easy fix. I'm getting the OK green status light from the Airport Extreme but cannot calibrate it to connect to the internet via the cable modem. The cable modem itself works fine standalone and I've been using it to surf the internet by directly plugging a LAN cable between it and the back of my iMac, so I know there's no problems with the modem itself.

Here's a bunch of screenshots.



Could someone please take pity on me!? Thanks in advance!



Bob.

Hi there,

I don't know the first thing about Macs or about computer networking but I'm hoping for some feedback about my network settings.

I have an iMac and have set up an Airport Extreme which is connected to a cable ADSL modem via a LAN cable. I've been fooling around with the settings and have screwed things up but I'm hoping if I get the numbers in the correct boxes it should be an easy fix. I'm getting the OK green status light from the Airport Extreme but cannot calibrate it to connect to the internet via the cable modem. The cable modem itself works fine standalone and I've been using it to surf the internet by directly plugging a LAN cable between it and the back of my iMac, so I know there's no problems with the modem itself.
I've included a bunch of screenshots.

Could someone please take pity on me!? Thanks in advance!

Bob.

 

[Morhass]

Hi Bob, you're so close!
Normally, your ADSL modem does DHCP, so you set your AirPort's Internet popup to DHCP. Let it get its subnet mask, router and DNS settings from the modem's DHCP... Hit update, and you should be away laughing!
Do let me know if this doesn't solve it though...

 

[BobBob]

Thanks for the quick reply Morhass!

I tried setting up a connection with DHCP as in the screenshot but the Airport is now flashing an amber error light.
Whenever I hit "Renew DHCP Lease" in either of these settings windows, neither will detect a Router Address.
I have no idea about IPv4 and IPv6 addresses, so is there something I'm overlooking?

Much obliged,
Bob.

 

[Morhass]

Hi Bob

drat, that _should_ have worked... That's assuming that your modem's IP is 192.168.01!

I'm guessing you used the same IP the Mac gets on ethernet when directly to the modem?

Two things spring to mind, we'll try the easy one first!

There are four ethernet ports on the back of the AirPort Extreme, three of them have standard ethernet symbols above them, but the left-most one should have a different symbol, a round one made of dots - thats the WAN port - it's the one that the cable to the modem has to be in…

While you're there, check that you get a tiny green light beside the port when the cable's connecting the two… that lets you know the physical connection's OK

 

[BobBob]

Thanks for the follow-up Morhass!

I tried using the same IPs that the iMac gets on the ethernet: both 192.168.0.1 and 192.168.0.2, but that didn't work.
I have the LAN/ethernet cable plugged into the correct socket on the back of the Airport and the small green light lights up after a few seconds to show the physical connection is okay.
I've also tried turning the Airport and modem on and off in different orders with DHCP active to no avail.
Have also tried countless times switching between manual and DHCP settings for both the Airport and the iMac's Wi-Fi utility.
Have also tried hitting "Renew DHCP Lease" in various orders.
I have the connection set up in "Bridge Mode" but I don't know if the Airport is serving as a router or not, and I don't really know what that means either.

BTW my OS is Mountain Lion and I've downloaded the latest firmware for the Airport.

Thanks for your patience!

 

[Morhass]

Hi Bob
Apologies for the delay getting back to you, I am away on holiday ATM.

You're right, normally you want the AirPort in Bridge mode so that it just passes on the information it gets from the modem.

It certainly looks like you've done everything correctly! At this point I have to conclude that the problem is in your modem. Unfortunately, every modem is different, and I've found some that simply refuse to hand out an IP number to an intermediate device like an AirPort or router... All I can suggest is that you log into your modem and see what you can tweak there...

If you can get the AirPort to talk to the modem, switch the AirPort from Bridge to DHCP and NAT so that it's providing the Mac with the necessary information...

You may find that the simplest solution is to replace your modem?

 

[BobBob]

Okay, thanks Morhass. I'm off for a business trip for a few days. So I'll see what I can do when I get back. Cheers.