Gigabit ethernet not working, but thunderbolt adapter is

Discussion in 'iMac' started by mdelrossi, May 22, 2019.

  1. mdelrossi macrumors member

    mdelrossi

    Joined:
    Jun 22, 2005
    #1
    Gigabit ethernet not working, but thunderbolt adapter is.
    The internal ethernet port only connects at 100baseT, however the thunderbolt to ethernet adapter connects at 1000baseT.
    Late 2014 5K iMac
    Mojave 10.14.5 New install , migrated settings and docs from previous system ( it stopped working a while ago with sierra, don't recall when)

    Ethernet:

    MAC Address:

    Media Options: Full Duplex, Flow Control

    Media Subtype: 100baseTX

    Proxies:

    Exceptions List: *.local, 169.254/16


    Any ideas?

    thanks
    mdr
     
  2. jerwin macrumors 68020

    Joined:
    Jun 13, 2015
    #2
    There's an option to configure the Ethernet Port manually or automatically.

    Screen Shot 153.png

    You can select 10BaseT,100BaseTX or 1000BaseT. Gigabit is the last option. I take it that you're plugging the same cable into the thunderbolt adapter?
     
  3. mdelrossi thread starter macrumors member

    mdelrossi

    Joined:
    Jun 22, 2005
    #3
    Thanks,
    I forgot to mention I tried to set it manually but it just disconnects.
    And yes same cable.

    thanks
    mdr
     
  4. HDFan macrumors 65816

    Joined:
    Jun 30, 2007
  5. mdelrossi thread starter macrumors member

    mdelrossi

    Joined:
    Jun 22, 2005
    #6
    Asus router, that's how I found out that I was not getting the proper speed, to Synology NAS(thats a whole 'nother ball of wax).
    Yea saw that and tried it, no help.
    thanks
    mdr
     
  6. HDFan macrumors 65816

    Joined:
    Jun 30, 2007
    #7
    Is there a way that you can run a test connecting directly to the NAS? That's exactly the problem that I had with my Cisco router/Firewall. It negotiated to 100 Mbps rather than 10 Gbps to my iMac Pro. Turns out it is a bug in the Cisco firmware so they had to create an enhancement request.
     
  7. mdelrossi thread starter macrumors member

    mdelrossi

    Joined:
    Jun 22, 2005
    #8
    I’m getting the info directly in the router status pane and in system report, so the problem is in the iMac.
     
  8. HDFan, May 23, 2019
    Last edited: May 23, 2019

    HDFan macrumors 65816

    Joined:
    Jun 30, 2007
    #9
    My Cisco router did exactly the same thing. The router port status table showed that the port was 100 Mbps rather than 1000 Mbps. It is then an open question as to whether it is a Mac issue or a Cisco issue. Since Cisco support created a feature request and didn't point their finger at Apple I assume that they felt that it was their problem.

    To illustrate I moved my iMac Pro ethernet cable from the 10 Gb QNAP switch to the Cisco port 2. You can see it shows as 100 Mbps. Note that the RV340 only supports 1 Gb.

    Screen Shot 2019-05-23 at 07.01.31.png

    but maybe I'm missing something here ...
     

    Attached Files:

  9. Fishrrman macrumors P6

    Fishrrman

    Joined:
    Feb 20, 2009
    #10
    Unless you need the thunderbolt port for something else, why not just "use what works best" -- the thunderbolt/ethernet adapter...?
     
  10. cube macrumors P6

    Joined:
    May 10, 2004
    #11
    What is the length and category of the cable?
     
  11. mdelrossi thread starter macrumors member

    mdelrossi

    Joined:
    Jun 22, 2005
    #12
    I'm getting 1000baseT speeds to the NAS ( as shown in activity monitor)with the Thunderbolt to Ethernet adapter.
    I'd like to not have to use thew adapter as i might need to use the TB port soon.
     
  12. cube, May 23, 2019
    Last edited: May 23, 2019

    cube macrumors P6

    Joined:
    May 10, 2004
    #13
    There could be a negotiation problem and the speed must be manually set on the switch.

    Also, a router may have different kinds of ports.
     
  13. antonypg macrumors member

    Joined:
    May 8, 2008
    #14
    I had an iMac that refused to work at gigabit speeds when connected to a couple of gigabit switches I had, worked fine at 100MBit. I took it to the Apple Store and they confirmed the fault, they swapped out the motherboard for free (still had AppleCare).
     
  14. HDFan macrumors 65816

    Joined:
    Jun 30, 2007
    #15

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