Ethernet has a self-assigned IP address and will not be able to connect to the Internet.

Question

Level 1

9 points

Ethernet has a self-assigned IP address and will not be able to connect to the Internet.

Whenever I try to connect to an ethernet connection on my Comcast Cable Modem, I get the following message in the Network Connections list: "Ethernet has a self-assigned IP address and will not be able to connect to the Internet." I see there are many posts related to this, but does someone have a definitive solution? My wireless connection through an Apple Time Capsule works fine, as does an ethernet connection at work. Thanks.

MacBook Pro (13-inch Mid 2012), OS X Mavericks (10.9.1)

Posted on Feb 12, 2014 5:16 PM

Reply

Answer 1

Linc Davis

Level 10

209,739 points

Feb 12, 2014 6:16 PM in response to daveA1A

Are the Time Capsule and the modem both configured as DHCP servers on the same network?

Reply

Answer 2

daveA1A Author

Level 1

9 points

Feb 19, 2014 2:23 PM in response to daveA1A

The Apple Time Capsule is configured as DHCP and NAT. I do not know how to check the configuration of the cable modem, which is actually a Motorola. Comcast Xfinity is my ISP.

Reply

Answer 3

daveA1A Author

Level 1

9 points

Mar 9, 2014 9:39 AM in response to daveA1A

OK, I think I know the root cause and the solution, after a lot of digging and experimenting.

First some background:

My ISP is Comcast (I am in South Florida)

I use an Apple Airport Time Capsule 2TB

I also use a Motorola SB6121 cable modem.

When I let the Time Capsule autoconfigure everything, under the Internet Tab and Internet Options mentioned, I saw that the Time Capsule allowed the IPv6 to configure automatically, and the "Enable IPv6 Connection Sharing" box was checked. This configuration was the situation that led to my original post where under the Network Settings in System Preferences, the ethernet connection was yellow, with the message "Ethernet has a self-assigned IP address and will not be able to connect to the Internet." displayed. Worse yet, the GlobalProtect VPN from Palo Alto Networks my company uses to allow me to connect remotely also did not connect either wirelessly or through the ethernet. The wireless network and non-VPN surfing was all fine. A lot of trial and error too long to list here ensued. Here is what finally worked:

I disconnected the power to the Time Capsule and disconnected it from the cable modem.
I unplugged the cable modem.
I powered up the Time capsule and did a reset (hold the reset button in for 7 seconds after it is powered up).
I connected the Time Capsule by ethernet cable to my MacBook Pro through the WAN port (labeled with small dots in a circle).
I did the setup again using AirPort Utility, but this time, under the "Internet" tab, I selected "Internet Options" and unchecked the box that says "Enable IPv6 Connection Sharing". I let the IPv6 remain connected automatically.
I completed the setup of the TC with AirPort Utility and now the light on Time Capsule is slow blinking yellow.
Next I powered up the Motorola SB6121 and when it had re-connected to Comcast and showed all lights on, I disconnected the ethernet cable from the MacBook Pro and connected it to the only ethernet port on the cable modem.

I got a green light, the VPN connected fine and the ethernet router ports on the Time Capsule connected and got an IP address for my MacBook Pro perfectly. My IT department also shared that they don't support IPv6, so that may have played a role in the VPN failure as well.

Bottomline, I am not sure if this problem originates with Comcast, the Motorola SB6121 or the AirPort Time Capsule. However, if the "Enable IPv6 Connection Sharing" box is checked, watch out!

Reply

Answer 4

Chiefted

Level 1

4 points

Mar 9, 2014 12:01 PM in response to daveA1A

Ok I'm not nuts. Same issues I am having.

If I plug my MBP directly to the Comcast Cable modem (Motorola Surfboard) I can connect on a wired network and have an Internet connection.

If I plug the Aiport time Capsule into the modem and then plug anything into my Airport Time Capsule, none of the wired equipment on my LAN gets a correct IP (they ALL get a self-assigned IP) and won't connect outside of my LAN. The Time Capsule in this case it connected to the modem.

I can connect wirelessly with the set up above (Comcast Cable Modem --> Airport Time Capsule ---> wireless network) but this option doesn't allow any of the equipment that needs to be wired to get an IP address. Its back to those device getting a self assigned IP address.

This started last Sunday after a reboot of all the network equipment (Comcast Modem and Airport Time Capsule) because I was getting self assigned IP addressses. I also rebooted my MBP just to be sure.. I did notice that the usual IP address group I got from Comcast had changef overnight on Saturday.

More trouble shooting. I replaced the Time Capsule with a brand new version (didn't solve the issue). I then went with a standard old router from Netgear. Same issue (wireless fine, wired not working). Tired a new modem from Comcast, same issue. Got a third modem from Comcast. This modem is the Ariss TG857. I now get wired connection and wifi without any issues. If I disable DHCP on the cable modem and let the Airport Time Capsule hadn out addresses, I am back where I started (wifi fine, wireless doesn't work).

If I unplug the modem from the Time Capsule it does hand out correct IPs (not self assigend) but, well, no Internet connection.

Since I went through all brand new equipment and still had the same issues, is it possible that the issue is with Comcast? It works with their equipment but the moment I put a third party router in the mix its self IP addresses for the wired network.

I see the suggestion above and will give that a try tomorrow. Right now it's working with the Comcast provide modem/router/phone modem/WAP but it still bothers me that for now I have to use Comcast's equipment

Reply

Answer 5

daveA1A Author

Level 1

9 points

Mar 9, 2014 3:02 PM in response to Chiefted

Try going thru the setup but uncheck the "Enable IPv6 Connection Sharing" on the Time Capsule. Let us know how it works for you.

Reply

Answer 6

Chiefted

Level 1

4 points

Mar 10, 2014 11:51 AM in response to daveA1A

Dave,

Will give that a shot. Right now its working with Comcast's gear but I don't like relying on them (the Tier II tech had no idea what a self assigned IP address was.....eek)

Reply