Title: Tahoe 26.6.2+ Wi‑Fi latency spikes (BCM4388 / M2 Pro) — video & VoIP call audio delayed; Ethernet & iPhone hotspot fine
Mac: 14" M2 Pro (Mac14,9), Broadcom BCM4388
AP: AT&T Fiber BGW320-500 (same gateway for months)
OS: 26.6.1 (25G76) was fine → 26.6.2 (25G83) broke it. 26.6.2 install logged 2026-09-11 23:58 CDT; first boot 2026-09-12 00:05:04. 26.7 (25G229) on Sept 15 did not fully revert.
Symptom: Meet / Trellus audio delayed. Browsing and speed tests look fine. Not packet loss — latency.
Wi‑Fi ping to gateway (192.168.1.254): ~3 ms baseline, 300–1300 ms spikes, 0% loss. Real-time audio dies on those spikes.
Controls (same Mac, same apps):
- USB‑C Ethernet via office switch → ~1 ms to gateway — clean
- iPhone 17 hotspot in the same room (−37 dBm) → Trellus zero delay, 0 dropped audio
- AT&T 5 GHz at −60 to −66 dBm → the stalls
Other devices on the same BGW are fine. This is the Mac’s Wi‑Fi hop.
Tried:
- BGW won’t lock 5 GHz channel (only “Find Best Channel”)
- Drop AX → N/AC: killed the ~1s stalls; Google worst latency 289 → 77 ms
- BT off: no help
- 40 MHz: made internet worse
- Forget network / Private MAC off: no fix
Looks like BCM4388 + Tahoe 26.6.2+ + ISP Wi‑Fi 6 at mid signal. iPhone on the same SSID uses N1 and the house “works.” Filed Feedback Assistant.
Looking for other M‑series + BGW320 (or similar ISP Wi‑Fi 6 gateways) with Meet/Teams/Zoom delay where Ethernet is fine.
