This is just an FYI in case someone else runs into this problem.
This afternoon (12 Dec 2025), I updated to macOS 26.2 and lost my network.
The System Settings' Wi-Fi light was green and said it was connected, but traceroute showed "No route to host".
- I turned Wi-Fi on & off.
- I rebooted the Mac.
- I rebooted the eero network.
- I switched to tethering to my iPhone.
- I switched to physical ethernet cable.
Nothing worked.
Then I remembered I had a beta of an app with a network system extension that was distributed through TestFlight.
I deleted the app, and networking came right back.
I had this same problem ~2 years ago. Same story:
app with network system extension + TestFlight + macOS update = lost network.
(My TestFlight build might have expired, but I'm not certain)
I don't know if anyone else has had this problem, but I thought I'd share this in case it helps.