Two VZM31-SN switches consistently stop communicating with ZHA roughly 12 hours after being reset or rejoined. Air-gapping restores them, but the problem repeats. A third identical switch remains online. They all have neutrals.
Setup: HA 2026.9.1, ZHA, HA Yellow, EmberZNet 7.5.1, channel 20, firmware 3.04.
What should I try next, and what logs or diagnostics would help identify the cause?