No gigabit ethernet connection anymore

Question

Level 1

5 points

No gigabit ethernet connection anymore

Hello,

I have a Macbook Pro retina mid 2012 and I used to have always a Gigabit Ethernet connection, but since a couple of weeks I only get 100 mbit. After reading in the forums that the cables can cause this I tried with new Cat 6 cables, I tested already 10 different cables and I only get 100 mbit. I tried those same cables connection a different PC and I always got 1 gigabit with the other PC.

Since new cables didn't work, I bought a new Thunderbolt adapter and the result is still the same, I only get 100 mbit. Sometimes when I connect the Macbook to my home network I get 1 Gigabit right after starting the macbook. While having a 1 gigbit connection it disconnects and re-connects several times until it finally stays at 100 mbit.

Speed and duplex of the Broadcom NetExtreme Gigabit Ethernet card are set on auto negotation. Any suggestions?

Posted on May 30, 2016 3:29 AM

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Answer 1

norm123

Community Specialist

May 31, 2016 9:55 AM in response to gcentineo

Hi gcentineo,
I understand that you are not getting your gigabit connection and it is topping at 100 mb for its speed. Let's see if we can get that sorted out.
One thing that comes to mind is that it could be a setting within the ethernet connection itself on your Mac. I would look at creating a new Network Location. This would allow you test out your connections without compromising any other setting. Take a look at the article below to walk you through this. Once you have created this and then plug in your Thunderbold Ethernet Adapter, then test to see if you get the same speeds.
Using network locations (Mac OS X v10.6 and later)
https://support.apple.com/en-us/HT202480
Let me know if this helps.
Have a good day!

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Answer 2

gcentineo Author

Level 1

5 points

Jun 1, 2016 12:14 AM in response to norm123

I think it is fixed now. I tested a few new cables again using the new adapter and some of them give me gigabit connection. It looks like it was a combination of the old adapter not working properly anymore and cable.

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Answer 3

norm123

Community Specialist

Jun 1, 2016 12:13 PM in response to gcentineo

Hey gcentineo,
Thanks for letting me know what the issue could be. Glad to hear that it is working for you now. If you have any other issues regarding this, let me know.
Thanks for using Apple Support Communities and take care.

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