"Ethernet has a self-assigned IP Address & will not be able to connect to the Internet"

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Level 1

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"Ethernet has a self-assigned IP Address & will not be able to connect to the Internet"

I just installed a new modem ( Arris Surfboard T 25) and using my Airport Extreme Router I get Internet. But if I try to connect directly to the Modem using my ethernet cable I receive a message in my Network Pane stating "Connected" but" Ethernet has a self-assigned IP Address and will not be able to connect to the internet"

I have tried adding a "New Location" in place of "Automatic"but status remains the same.

What should I do?

Mark, MacBook Pro 2013 MacOS Mojave 10.14.6

MacBook Pro 13″, macOS 10.14

Posted on Aug 27, 2020 11:21 AM

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Answer 1

Top-ranking reply

Bob Timmons

Community+ 2024

Level 10

168,536 points

Aug 27, 2020 5:06 PM in response to MarkSpotKick

I've asked you to power off the modem for a time because cable modems behave in a particular way. They only "remember" the device that they have been previously connected to, so when you connect your Mac directly to the modem, the modem is still looking for the AirPort Extreme. It can't find it, because it only knows to look for the AirPort Extreme.

So, you have to reset the modem so that it will "forget" your AirPort Extreme and "associate" with your Mac to set up a new connection. The extended power down resets the modem and gives the equipment back at the cable company time to reset as well and issue a new fresh connection.

That is why it is very likely that you will have to go through the modem power down process again when you want to connect the AirPort Extreme back to the modem.

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Answer 2

Aug 27, 2020 11:49 AM in response to MarkSpotKick

If your AirPort Extreme is working correctly, not sure why you want to connect your Mac directly to the modem.

Did you remember to power off the modem, leave it off for 10-15 minutes, then power it back up......before......you attempt to connect your Mac directly to the modem? Even better.....restart your Mac again before you connect it to the modem.

Here's the whole deal.......

Power off the modem completely by pulling the power cable from the back of the device or from the AC wall socket, whichever is easier

Leave the modem off for 10-15 minutes. Longer will not hurt and in some cases will be necessary depending on your Internet Service Provider.

After the 10-15 minutes of power down, power up the modem and let it run for a few minutes by itself

Restart your Mac

Connect your Mac to the modem using the Ethernet connection.

When you reconnect the AirPort Extreme to the modem again, you will have to go through the same process as above, just substitute the AirPort Extreme for your Mac.

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Answer 3

MarkSpotKick Author

Level 1

13 points

Aug 27, 2020 12:12 PM in response to Bob Timmons

Thanks, I will try this, and thank you for you very prompt response.

As you say why bother if my router /network works properly. Answer is that this is an old Extreme router which I have just discovered is only giving me 40% of my internet speed, so I was verifying the speed.

So, I am buying a new router - another Airport Extreme, this is the 6th Generation ( apparently "New" not "refurbished" according to the Amazon Vendor) and I just wanted that contingency of directly accessing the Internet using an ethernet cable, if something should go awry on the router front.

PS

The T 25 modem has 2 ethernet ports so I think I won't need to disconnect the router when powering off for the first time.

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Answer 4

Aug 27, 2020 1:19 PM in response to MarkSpotKick

this is an old Extreme router which I have just discovered is only giving me 40% of my internet speed, so I was verifying the speed.

Old or new, the AirPort Extreme will top out at about 300-325 Mbps as far as its Internet connection speed.

The T 25 modem has 2 ethernet ports so I think I won't need to disconnect the router when powering off for the first time.

I haven't tested that particular modem, but you may still need to go through the power down and up process whenever you change the device that is connected directly to the modem.

As far as a "new" AirPort Extreme, Apple discontinued the Extreme in AprIl 2018 and sold off the remaining inventory at that time. It's possible that an AirPort Extreme could be "new", but it has been sitting on a shelf somewhere for well over 2 years.

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Answer 5

MarkSpotKick Author

Level 1

13 points

Aug 27, 2020 1:43 PM in response to Bob Timmons

I'll be happy with 300 Mbps as that is the speed I have purchased.

And,Yes, thank your the heads up.... I was aware that Apple got out of the router business, so I agree "new" isn't exactly new. However my "old" Extreme router is over 12 years old, and it still delivers 95-100 Mbps. I have never had problems with it and but for it aging gracefully , ( to a slower speed) I wouldn't change. But if a change is made i decided to try my luck with the "new" Extreme.

I will let you know tomorrow if your suggestion fixes my particular problem, and as you say it's really not a problem when the Modem/ Router/LAN all work just fine.

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Answer 6

MarkSpotKick Author

Level 1

13 points

Aug 28, 2020 1:35 PM in response to Bob Timmons

Thank you, for your precise instructions. you have resolved my small problem.

Indeed, you have been right all along. I did power down the modem and connected with my laptop via ethernet cable. And just as you pointed out I had to repeat the same process to reconnect to the Airport Extreme, by powering down the modem a second time.

Any I now understand the issue, which is new and strange because my old modem, likewise a 12 year old Arris 3.0 DOLCIS allowed me to jump from router to laptop and back again without interruption.

That is why I posted my concern. Looks like the new modems stick to the rule you highlight -only one connection remembered.

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Answer 7

Aug 28, 2020 2:09 PM in response to MarkSpotKick

Nice work. You might be able to get away with a shorter power down period for the modem, it all depends on your Internet Service Provider and how fast their equipment will reset and issue a new fresh connection.

A really good provider will reset the modem quite quickly, maybe as quick as a few seconds. A not so good provider will sometimes take 30 minutes or more before the modem will reset.

I suggested the 10-15 minute power down since that will cover just about all but the slowest providers. If you have the time, you can find out how quickly your provider will reset things. It might be as quick as power off the modem, count to ten, and power up again.

Your new AirPort Extreme should be able to handle a 300-325 Mbps Internet connection pretty well, but it won't go much higher. If you see 100 Mbps, that would usually indicate a bad Ethernet cable. A bad cable will still allow a connection, but limit speeds to 100 Mbps.

Would be interested to see how the new Extreme is doing when/if you have a chance to post back.

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Answer 8

MarkSpotKick Author

Level 1

13 points

Aug 28, 2020 4:25 PM in response to Bob Timmons

OK will do.

I get my new Airport Extreme, next week ... sometime between 1st & 4th Sept.

I will remember to let you know what my final out come is...... when it comes to the ethernet cable connection to my new router.

The current cable is buried in the wall through 2 floors, but it is a 5e cable, so should be adequate.

My Service provider is of course Comcast, since I live in Philadelphia PA, and their power down/ reset is 10 seconds. I used a 30 second break to make sure during the recent powering down you suggested I go through, and it worked.

So, bye for now, and My next post to you will be when I have the new Extreme in place and the outcome in internet speed.

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Answer 9

MarkSpotKick Author

Level 1

13 points

Aug 30, 2020 12:13 PM in response to Bob Timmons

Hi, Bob

So here's my news

My new Airport Extreme arrived this morning, and I and our LAN are happily connected in place of the old retired Extreme.

The new one, is exactly as advertised - NEW; still in it's original Apple packaging and box.....recognizing it was manufactured in 2017 or 2018

I can confirm the the top speed we get is 350 Mbps - which is the top Xfinity Comcast delivered speed. My wife's MacBook Pro is a 2016 model which has wireless 802.11ac and she get's this speed anywhere. - ( my Airport Utility advises Data Transfer up to 750 Mbps available to her machine)

I have the old 2013 MBP and I have only 802.11b/g/n, so my max. Data transfer available is 300 Mbps, and my actual connection speed tops out at 220 Mbps, where I normally use it. Nearer to it, in our bedroom annex where the Extreme is located, I get 250 - 290 Mbps. Also if I connect with an ethernet cable to one of the Router LAN ports I also get 350 Mbps. So the limitation is my machine. All of this also applies to our phones and iPad's depending on age and whether their connection is 802.11ac or not.

So very pleased with the end result.

And once again, thank you for talking me through the finer points of today's modem connectivity issues

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Answer 10

Aug 30, 2020 12:26 PM in response to MarkSpotKick

Thanks for posting back.

Good news! Looks like the new AirPort Extreme has done the trick! Excellent performance.

Glad that we could help on the modem checks.

If you have not already done so, you might want to make sure that the new AirPort has the latest firmware installed. That would be 7.9.1, which became available about a year after Apple stopped producing the AirPorts, so a new factory sealed unit would be running an earlier version of firmware.

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Answer 11

MarkSpotKick Author

Level 1

13 points

Aug 30, 2020 12:58 PM in response to Bob Timmons

Yes the Airport Utility/Extreme prompted me during set up, and I confirm I now have the 7.9.1 Firmware installed

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"Ethernet has a self-assigned IP Address & will not be able to connect to the Internet"

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