> One is that if it has been using WI-FI and I plug-in my dock with an Ethernet cable attached, I lose internet access because MacOS can't gracefully handle the new interface becoming available.

macOS has a 'service (priority) order':

* https://sixcolors.com/post/2025/05/service-please-manage-mul...

It's no different that having multiple default gateways in Linux (with different metric/priorities):

* https://superuser.com/questions/1600190/change-order-of-rout...

And when your default route changes so will the TCP connection end-points. This is mostly an issue when you have a stateful session, like SSH, and less so with 'bursty' traffic like web surfing or e-mail.

By default wired connections are higher priority. I've been on Wifi with a MacBook and patched in with the Network Settings panel open and see the change, which is reflected in the output of "netstat -rn". Underneath the hood most of the macOS kernel is (Free)BSD/Unix.

Until we get SCTP multihoming popularized this will generally be an issue on any operating system. Though it would perhaps be nice to perhaps have a socket (TCP) API flag to tell the kernel "keep me on the initial interface as long as it exists" so sessions don't flip over.