Ethernet Ports Stop Working

Hello, me again.

I just wanted to give a update on this issue, since i've been continuing to tackle it. I really think this is a driver issue that is neglected by Apple. I recently abandoned macOS on the Mac Pro 3,1 since it is not supported beyond El Capitan, and installed Windows 10 straight up without using boot camp on the 2nd internal disk using a Windows 10 DVD. Well guess what, the ethernet ports are working just fine and dandy for well over a month now. I realize that this is probably not a solution for most people here but i thought i would point out that discovery. For my purposes, all the apps i need to use are also available for windows. On the hardware side, everything seems to work perfectly on the Mac Pro with Windows 10 except the built in speaker and built in bluetooth, but for my purposes as a headless server, that's a non-issue. I much prefer the stability.

What i had been doing before installing windows 10 is i had setup an automator script that would make the ethernet ports inactive and active again, twice a day. My specific issue would get resolved simply by going into system preferences and making the afflicted ethernet interface inactive, then active again. So with an automator script running on the calendar app every 12 hours it was as close as i could get to having consistent network uptime. But then came the time that the ethernet port failed soon after the script had run, and there was a downtime of almost 12 hours. So to **** with the workaround and hacks, i decided to give Windows 10 on the Mac Pro a try as i found a few articles online saying it worked well. I'll give it a few more weeks and then i'll wipe the 1st disk with macOS on it and use the space for Windows.

I used to have more macOS machines running in the house than Windows, this install just turned the tide.

Random hardware issues are very difficult to troubleshoot (no surprise to you, I am sure). I would reset the SMC...cannot hurt, might help.

Barry

SMC reset is my recommendation as well.

Shutdown.

disconnect AC power cord. wait overnight --or if impatient:

... press the power on button for about ten seconds to discharge the power capacitors.

restore the AC power cord (there are some "always-on" power supplies inside, so it may spark at reconnect).

wait a quarter minute for all to settle.

Power on as usual.

try:

System Preferences > Network > Ethernet > ( assist me ) > ( diagnostics )

Hi all.

I am having this exact same issue. There is another thread about it here :network port hangs
it seems to be triggered by heavy network traffic using the ethernet port(s). It just happened to me now while trying to backup GB's of data....

I also have a 2008 mac pro with el capitan and when the issue arises, the ethernet port loses connection to the network and assigns itself a self-assigned ip address. I can change the ethernet cable to connect to the second ethernet port and then regain a connection to the network and continue until the problem eventually occurs on that port as well. The only way to fix the issue seems to be a reboot.

I am at a loss of what to do, it's frustrating that my server cannot reliably use its ethernet ports. I might simply take the hit on network speed and use the wireless network card instead.

For what it's worth the router that the mac pro is connected to is the latest airport extreme model at the time of this writing.

This post on apple stack exchange seems related http://apple.stackexchange.com/questions/158931/why-does-my-wired-ethernet-conne ction-die-periodically-after-a-dhcp-leas…

Lower down in the post it describes the issue occurring more often when transferring large files to the server

Do you have both ethernet ports active ( both have a cable plugged in) perhaps that is why they both fail at the same time. I only use one port. I will double check the next time it happens if the address falls to a self-assigned. Currently my en0 has the problem but i changed the cable to en1 and I'm waiting for the issue to reproduce.

I agree it that it can manifest randomly even with little or no traffic, however this usually takes a few weeks for me. Increased traffic seems to increase the chances.

Well it happened on en1 now. The interface changed to a self assigned ip address. I tried the "assist me" and diagnose the ethernet ports, but it says that it seems to be working fine.

I tried changing the ethernet configuration to DHCP with manual ip address, but that did not seem to help and didn't result in a network connection.

I suppose I could sift through the system logs and try to find something.... painful.

I'm also gonna try with manual network settings and see if the problem arises after a reboot again.