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My Mac can't seem to get a DHCP IP.

cbrain

cbrain

macrumors 65816
Original poster
Hi.

My Mac suddenly cannot get a DHCP IP from my router. I have tried restarting the router, modem and the Mac. I am typing this from my old PC.

Any suggestions?

Thanks.
 
cbrain said:
Hi.

My Mac suddenly cannot get a DHCP IP from my router. I have tried restarting the router, modem and the Mac. I am typing this from my old PC.

Any suggestions?

Thanks.
Click to expand...

A few more details would help us help you.

Is it a wireless router? When you bring up system preferences, does your mac show a self-assigned address (and an amber dot on Network status) or a good address (and a green dot on Network status).

Can you ping your router from your mac?

I am not sure what your problem is, but I hope that helps.
 
You have checked all of the obvious things, right?

1) The full connection path
2) Cabling (make sure Fido did not chew through a wire)
3) Light On at switch/router and Mac

If all of the connections are OK, put in a static IP and see of you can raise the router/gateway/switch (depending on your set-up). If nothing is working yet, try a straight peer-to-peer ping between the Mac and PC, with static IP's. Ethernet cards, even embedded, are pretty reliable. But, they will occasionally fail.
 
It is a wireless router but I am connected via ethernet. I tried wireless but that won't work either. Built in ethernet is amber. It sais it is connected but has a self assigned IP. I can't get on the web though. I don't have any pets to chew through wires and I have checked all the cabling.

Thanks.
 
What happens when you ping the router's IP address (typically 192.168.1.1 or a similar address- check your router manual.)

Either your cable is bad, or your router is no longer serving DHCP to your internal network.

If you haven't set up a lot of specific wireless and port forwarding stuff, then it may be worth it to reset the router to defaults, change the Admin logon and password 1st thing, then do the setup from scratch. (check the router manuals)
 
When I put the routers IP into Firefox on my mac it just hangs on "Connecting to 192.168.1.1". However, my PSP, PC and Xbox 360 are working perfectly fine with the router.
 
cbrain said:
When I put the routers IP into Firefox on my mac it just hangs on "Connecting to 192.168.1.1". However, my PSP, PC and Xbox 360 are working perfectly fine with the router.
Click to expand...

Then, if 192.168.1.1 is the correct address for your brand of router according to your manual, you have a bad Ethernet cable or a blown port on the router or something Fubared with your Mac's Ethernet connection. Can't help any further without more details.

1) establish that your Mac's ethernet connection is turned on and works
2) replace the cable
3) establish that you can ping the router.
 
Well, I tried it on a different port on the router but it didn't work then either, but there is a light on the router stating that a cable is connected. I'll try a different cable, but when I tried connecting wirelessly, it didn't work then either, but I shall try a different cable.
 
Also make sure your Mac's MAC address is allowed and not being blocked in your router's web-based setup. And if you have static DHCP enabled in your router, make sure your Mac is in the list to get an address assigned to it.
 
Kenny Rullo said:
pick your attention on cable feature. PC -> Router connection needs a flat cable, PC -> PC connection instead needs a crossover cable.
Maybe you're using a cross cable in your lan with router.
Check this out:
http://en.wikipedia.org/wiki/Ethernet_crossover_cable

If not, try to test your mac built in ethernet, or test your router ports, they may have troubles.
Click to expand...

No that is not correct. All modern Macs auto sense the Ethernet cable and do an automatic crossover if necessary.

Also the OP already stated they are trying it with a cable.

SuperMachoMan:
Until the OP actually give us accurate information about how the Mac is configured, it's pointless to keep guessing.

cbrain: Enough with the "It doesn't work" . If we are going to help you, we need the details. Please answer the following questions:

#1: Do you have the router manual? Have you checked the actual internal IP address of the router's admin? This will vary by make and model.
#2: What EXACTLY are the current settings of the Mac's Network settings? Post all of them please.
#3: Use your PC to access the router's admin page at its internal IP address. What are the DHCP settings of the router? This will vary by router make and model, so we can't guide you.
 
Now, what is really strange, is that I can acces the internet through Kubuntu in Paralels, on my mac, thats what I'm doing now!

1. That is deffinetly the routers IP as I have used the setup facility many times for things like port forwarding.
2. My iMac is configured like this:
Location: Automatic
Show: Built-in Ethernet
TCP/IP
Configure IPv4: Using DHCP
IP Address (self-Assigned by the way): 169.x.x.x
Subnet Mask: 255.255.0.0
Router: (Blank)
DNS Servers: (Blank)
Search Domains: (Blank)
3. These are the DHCP settings:
DHCP Server: Enabled
Starting IP Address: 192.168.1.100
Maximum Number of DHCP Users: 50
Client Lease Time: 0
Static DNS 1: 0.0.0.0
Static DNS 2: 0.0.0.0
Static DNS 3: 0.0.0.0
Static DNS 4: 0.0.0.0
WINS: 0.0.0.0

If theres any more info thats required I'll be able to find it, hopefully.
 
The Mac OS is not seeing or communicating with the DHCP server in the router. Try setting it to manual, and putting in the router/gateway address (192.168.1.1) and a manual address for the Mac (192.168.1.109 for example -- whatever is not taken by the other devices.)

There may be a .plist file you can throw out in case your networking prefs are corrupted - try
HD: Library: com.apple.NetworkConfig.plist
 
Greetings,

I tried throwing out that plist but it didn't do any good.

I can see where to enter my macs IP but not the routers. The "Router:" Field has no typing box. When I gave the computer a manual IP, Built-in Ethernet went green. However, I still couldn't acces the internet. It came back on red when I ran Network Diagnostics.

Thanks.
 
I've seen this

My mom's iMac (20", C2D) had this problem once, and it totally puzzled me. There was no router, the cable modem was directly plugged in. The iMac ended up with a self-assigned IP (169.x.x.x).

I was able to fix it by restarting the iMac with extensions off (hold shift at startup right after the chime). With extensions off, the network came back to life. It's now working fine in normal mode.

It this doesn't work, try resetting the PRAM (hold cmd-opt-p-r right after the chime until you hear the chime again).

Hope this helps!
 
Echoes,

Unfortuantly, that didn't work.

I can't see anyware in my routers setup where I can see if it's blocking my mac. It's a linksys by the way.

Built in Ethernet is now on green but I still can't access the internet, I can only acces the routers setup page.

Any more suggestions?

Thanks.
 
I have now tried reseting the router to its factory defaults. It didn't work. I'm getting really annoyed about this problem now; I'm just sick of starting Paralels whenever I want to access the internet.
 
I have now reinstalled OS X, it didn't fix it. Time to ring Apple? Or do you have any more suggestions?
 
cbrain said:
Now, what is really strange, is that I can acces the internet through Kubuntu in Paralels, on my mac, thats what I'm doing now!
Click to expand...
I don't know why no one else picked up on this. This clearly points to a software issue on the Mac — I'd say even that it's probably Parallels somehow hijacking the Mac's network connection.
cbrain said:
I have now reinstalled OS X, it didn't fix it. Time to ring Apple? Or do you have any more suggestions?
Click to expand...
What kind of install did you do? Archive & Install? Did you try uninstalling Parallels?
 
I did Archive and Install, I have had Paralells for quite a while now, but why would it suddenly mess my mac up? I'll try unistalling Paralels.

Thanks.
 
The Parallels un-installer claims that Parallels isn't installed, although it is. When I try to launch Parallels, it complains that it is having trouble locating one of its drivers.
 
Any other recent changes to your Mac or your network that you can think of?

This might be obvious, but, have you tried going to the System Network Preferences and clicking "Renew DHCP Lease"? Are all your TCP/IP settings correct?
 
The only changes I can think of is that I updated my routers firmware a few days ago.

I have tried renewing the DHCP lease but I shall try again........no, it didn't work, it got an IP, but it still can't connect to the internet. When I went into the preferences, I noticed that Parallels Host-Guest and Paralells NAT connections have gone.

Any more suggestions?

Thanks.
 
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