Re: IPv6 networking problems in 14.3

> On Sep 18, 2025, at 16:36, Chris Ross <cross+freebsd@distal.com> wrote:
> 
>> On 17 Sep 2025, at 14:20, Chris Ross <cross+freebsd@distal.com> wrote:
>> So, on the idea of trying to back-date the whole machine, I have ZFS
>> snapshots of the whole root from just before the first upgrade,
>> Aug 7/8.  […]
> 
> [...]  I’ve set bootfs to the older 14.1 system and gotten that running.
> 
> It [...] out SOLICIT6 messages and [..] if I waited long enough (2ish
> hours in my case), it eventually did get an answer!

And, this is where things went odd again.  The above attempt in older
filesystem, I had during boot menu chosen my ROUTER custom kernel.  Just
a config I traditionally use that has fewer devices in it occupying memory.
So, thinking it shouldn’t make a difference I rebooted into the default,
GENERIC, kernel on the system.  The default kernel had problems [1], so I
chose the boot/kernel.generic on the fs.

Sadly, it did not work.  I get the same state where the router LL is
unroutable, ndp -an shows no MAC for it, and I have no IPv6.  So,
despite thinking the kernel config wasn’t key detail, I booted back
into kernel.router.  Now I have no IPv6 there either.  I tried just
shutting down dhcpcd overnight to see if it ISP was confused, but no help.

So, it certainly could be the ISP, but the fact that I’m getting RA’s
(and dhcp6 responses) which dhcpcd is processing, but then the MAC for
the routers LL isn’t available to the system, makes me think it’s _not_
the ISP.  I can’t imagine why a working rootfs and kernel could
show a system level problem intermittently, though.

Thoughts again invited.  Not able to reproduce success now, I don’t
know that I can actually _test_ anything, but I’d love to hear thoughts
about any options/possibilities.

                   - Chris




[1] Sadly there is something wrong with /boot/kernel in that fs.  When
  I boot it I get a number of:

  KLD uhid.ko: depends on kernel - not available or version mismatch
  KLD ums.ko: depends on kernel - not available or version mismatch
  KLD usbhid.ko: depends on kernel - not available or version mismatch
  KLD uhid.ko: depends on kernel - not available or version mismatch

  errors late in boot.  That kernel is 14.1-RELEASE-p7 (despite the fs
  freebsd-update made named zroot/ROOT/14.1-RELEASE-p8_2025-08-08_074410).
  The rest of the kernels I have on the fs are 14.1p5. something must be
  off with that one.  So I booted /boot/kernel.generic, 14.1p5, and it
  boots fine.

Current output log of dhcpcd: note "fe80::3e8a:b0ff:fe3e:4dce is unreachable”.
That’s a kernel routing issue, and I think the primary problem.

Sep 20 10:20:32 [30273]: vlan0: REPLY6 received from fe80::3e8a:b0ff:fe3e:4dce
Sep 20 10:20:32 [30273]: vlan0: renew in 3600, rebind in 5760, expire in 7200 seconds
Sep 20 10:20:32 [30273]: lo0: adding reject route to 2600:4040:2c9c:2d00::/56 via ::1
Sep 20 10:20:32 [30273]: vlan0: writing lease: /var/db/dhcpcd/vlan0.lease6
Sep 20 10:20:32 [30273]: vlan0: delegated prefix 2600:4040:2c9c:2d00::/56
Sep 20 10:20:32 [30273]: vlan0: executing: /usr/local/libexec/dhcpcd-run-hooks BOUND6
Sep 20 10:29:08 [30273]: vlan0: Router Advertisement from fe80::3e8a:b0ff:fe3e:4dce
Sep 20 10:29:08 [30273]: vlan0: no global addresses for default route
Sep 20 10:29:08 [30273]: vlan0: executing: /usr/local/libexec/dhcpcd-run-hooks ROUTERADVERT
Sep 20 10:30:15 [30273]: vlan0: fe80::3e8a:b0ff:fe3e:4dce is unreachable
Sep 20 10:30:15 [30273]: vlan0: delaying IPv6 router solicitation for 0.7 seconds
Sep 20 10:30:16 [30273]: vlan0: soliciting an IPv6 router
Sep 20 10:30:16 [30273]: vlan0: sending Router Solicitation
Sep 20 10:30:16 [30273]: vlan0: Router Advertisement from fe80::3e8a:b0ff:fe3e:4dce
Sep 20 10:30:16 [30273]: vlan0: executing: /usr/local/libexec/dhcpcd-run-hooks ROUTERADVERT