Public bug reported:
On kernel 6.17.0-14-generic, the Qualcomm FastConnect 7800 (WCN7850) Wi-Fi
adapter is completely unable to detect or connect to 5GHz networks. Only 2.4GHz
networks are visible. The issue does not occur on kernel 6.14.0-37-generic,
confirming this is a 6.17 regression.
Symptoms:
No 5GHz networks appear in scan results (nmcli dev wifi list / iwlist scan)
Repeated "received scan start failure event" in dmesg
Throughput dropped from ~600 Mbps (5GHz on 6.14) to ~60 Mbps (2.4GHz only on
6.17)
phy#0 self-manages regulatory domain, setting country 00 with all 5GHz channels
as PASSIVE-SCAN only
Hardware:
Qualcomm WCN785x Wi-Fi 7 FastConnect 7800, PCI 0000:09:00.0 rev 01
Subsystem: Foxconn International
Firmware: WLAN.HMT.1.1.c5-00284.1, build 2025-05-17
Driver: ath12k_pci (compiled into kernel, not a module)
Kernel log (6.17 boot):
```
ath12k_pci 0000:09:00.0: received scan start failure event
ath12k_pci 0000:09:00.0: received scan start failure event
ath12k_pci 0000:09:00.0: received scan start failure event
ath12k_pci 0000:09:00.0: received scan start failure event
```
Additional notes:
No ath12k firmware packages were updated prior to the regression
ath12k on 6.17 only exposes debug_mask and ftm_mode module params — no
regulatory override available
country_code and reg_proto_off params are silently ignored
Workaround: Booting kernel 6.14.0-37-generic fully resolves the issue.
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: ath12k kernel-6.17 regression wifi
** Tags added: kernel-6.17 regression wifi
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https://bugs.launchpad.net/bugs/2143056
Title:
ath12k/WCN7850 (FastConnect 7800) 5GHz scan failure on kernel 6.17 --
works on 6.14
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