Kernel Panic (Kernel tag check fault) during PPPoE Connection on macOS Tahoe 26.3 (25D125)

啟惟 wrote:

To clarify the context:

Previous Setup: MacBook Pro M3 Pro + macOS 26.3 → • No issues.

Current Setup: MacBook Pro M5 + macOS 26.3 (pre-installed) → • Kernel Panic.

Since the OS version (26.3) is identical, but the behavior changed after upgrading the hardware, could this be related to how the M5 architecture handles legacy networking drivers? Is it possible that the M5’s enhanced hardware security (such as PAC or Memory Tagging) is flagging a conflict in the com.apple.nke.ppp driver that the M3 Pro didn't intercept? I'd appreciate any insights on M5-specific compatibility.

If you can, I suggest making an appointment to take your M5 laptop to an Apple Store or Authorized Service Provider where you can show them the fault in person. I think that will work the best to get appropriate attention on the issue (or they might help you resolve it). If there might be a hardware fault you would eventually have to do that anyway.

啟惟 wrote:

Actually, I am not using any Ethernet cable or adapter at all. I am initiating the PPPoE session directly over the built-in Wi-Fi interface.

My Mac connects to the ISP modem via Wi-Fi (in bridge mode), and I trigger the PPPoE connection within macOS settings.

The kernel panic occurs in this purely wireless configuration, which rules out any third-party USB-C adapters or hardware hubs.

Are you saying this is a new issue with the point-update: < macOS Tahoe 26.3 > or you just upgraded to Tahoe(?)

this is not clear unless I missed something...

See if there is any clarification here

ref: Connect your Mac to the internet using PPPoE

https://support.apple.com/en-bw/guide/mac-help/mchlp27142/mac

You can escalate the issue up the chain of command if no insight or resolve by Tier One (Frontline) Support:

Call Customer Support (800) MY–APPLE (800–692–7753)

or on line https://getsupport.apple.com/

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

https://support.apple.com/en-us/HT201232

啟惟 wrote:

Hardware Status: Verified healthy via Apple Diagnostics (Result: ADP000• )

Apple Diagnostics: The test completed with no issues detected (ADP0001. ), ruling out physical memory or logic board failure.

FYI, a passing diagnostic result does not indicate the hardware is healthy. It just means that the tests did not trigger a hardware failure. The only useful diagnostic result is one which produces an error code.

Besides, the current Apple Diagnostics are a joke (including the service diagnostics....the consumer Apple Diagnostics with Tahoe are basically the same as the service diagnostics these days for an M-series Mac). They really only check to make sure certain hardware is present & communicating. The cooling system test is probably the main test which actually does a decent job. The memory test is very basic and only takes a few minutes to run. That is about it. Not much testing is actually done. In my experience, either memory failures occur frequently, or it may take hours of use before a memory failure will be triggered. Unfortunately at this time, the Apple Diagnostics are our only option on an M-series Mac.

the issue persists on a clean install of build 25D125, this appears to be a regression or a severe bug in the macOS Tahoe networking stack's handling of PPPoE packets on Apple Silicon.

It either indicates a hardware issue or a severe bug. Unfortunately there is no way to know for sure unless others can reproduce the Kernel Panics. I imagine @Barney-15E is correct, that probably not too many people are using such a PPPoE configuration these days.

In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment

Make an appointment for a "hardware issue"

https://www.apple.com/retail/geniusbar/

Outside the USA

https://support.apple.com/en-us/HT201232

What do you consider a, “full system reset?”

Reinstalling macOS does not remove any third-party software or system modifications. If you completely erase the disk and reinstall and not install anything else, including migrating your data, then it would be pristine. Since it also panics and safe mode, that would indicate a hardware problem. Do you have any external devices connected like some sort of network dongle? That could be a possible cause of the hardware fault, but I imagine it would be difficult to test this problem with it disconnected.

Apple diagnostics does not check for anything that would cause a kernel panic. You would have to take it to an Apple Store or Apple authorized repair center in order to evaluate that kind of hardware fault.

I don’t have any way to test. It could be a problem with an Apple kext, but that is rare. I’m not sure how many people use PPPoE, but imagine it isn’t t a lot, so hard to determine ignite is a problem with the kext.

What are you using to connect the Ethernet cable? That could be the hardware that is causing the panic.