Fedora 23: IPv6 not working with Dell DW1525 (ath9k)

[Laurențiu Păncescu]

Hi there,

I upgraded a Dell Vostro 260 desktop PC (with a Dell DW1525 wireless
card for network connectivity, using an Atheros AR9280 chip) from
Fedora 22 to 23. IPv4 continued to work, but IPv6 packets seem to go
into a black hole, even ping6 or ssh. I added ipv6.disable=1 to the
grub configuration as a workaround, but I'd like to understand what's
going on.

I booted both the PC and a netbook (having an AR9281 wireless card,
which also uses the ath9k kernel driver, connected to the same
wireless router) from the same Fedora 23 Workstation live image: IPv6
works perfectly on the netbook, but not on the PC. Fedora 22 and 21
worked fine, too. I also tried to boot F23 on the PC with the 4.2.6
and 4.2.8 kernels from F22, but IPv6 doesn't work in this
configuration, either.

Any idea what might be wrong? I could attach the full output of lspci
-vvnn if it's useful:

03:00.0 Network controller [0280]: Qualcomm Atheros AR928X Wireless
Network Adapter (PCI-Express) [168c:002a] (rev 01)
	Subsystem: Qualcomm Atheros DW1525 802.11abgn WLAN PCIe Card [AR9280]
[168c:0203]

Thanks,
Laurentiu