I have a few ESP32/8266 devices added to HA via ESPHome, or directly (e.g. via WLED integration).

The devices seem to go unavailable quite frequently, for long periods of time.

I have an OPNsense router, and Deco mesh wifi. The odd thing is when the devices go unavailable, they are not pingable on the network, but in the Deco app, they show connected with good signal and the correct IP address. It's almost like they're on the network but not responding to anything.

I've tried giving everything static IP addresses, and had a very stable period for a few days where the devices would only go unavailable in the HA log for a few seconds at a time. That was until a power cut today when all the devices seem to be misbehaving again, and I'm having serious problems getting them to remain on the network for any length of time.

I feel I must be overlooking something simple. I have all the advanced stuff (fast roaming, beamforming, etc.) turned off on the Decos. I have mDNS enabled on the OPNsense. Every other device on my network behaves itself except the ESP devices.