Intermittent packet loss on M1 iMac ETHERNET adapter
We have many 2022 M1 iMacs that are experiencing intermittent packet loss (up to 80% sometimes).
WiFi is turned off, IPV6 is set to local-link, Switch and router all function properly. Cables all test good. We are using Monterey because OS X Ventura breaks our software so I am not able to do an update.
When the problem occurs, I plug in a USB-C Ethernet adapter and take the same ethernet cable from the Power Brick, plug it into the USB-C Ethernet adapter and network is 100% Stable and packet loss is zero.
I can duplicate the problem by trying to transfer a file to another machine on the network, or doing a download. Sometimes it only transfers about 10MB of a 700MB file then stalls and all the network apps start to time out and fail. JUST ON THAT MAC. Switching to the USB adapter fixes the problem. Doesn't matter if the iMac is set to use DHCP or a Static IP address.
This is happening to all of our M1 iMacs intermittently. And it's usually one or two iMacs at a time.
It seems that there are lots of people reporting this issue, but no one has a real solution other than using an external Ethernet Adapter. So I think it's a bug. Unfortunately the Apple Feedback page just kind of tells you to take a long walk on a short pier.