ESPHome Dashboard shows devices Offline in containerized TrueNAS Scale environment despite devices being reachable and OTA working

[romcek]

Version

2025.12.5

What type of installation are you using?

Docker

Browser

Firefox

What happened?

ESPHome Dashboard shows all devices as Offline
Devices are reachable via IP and hostname
Ping works from inside the container
OTA updates work
Logs stream correctly
Home Assistant shows devices Online
Only the Dashboard UI is incorrect

How to reproduce

1. Add new device in ESPHome
2. Configure device with initial/minimal or any other configuration
3. Install/upload code to device
4. device stays offline for days
5. Device is in reality online. Ping, OTA, logs are working. Device is present in HA.

Expected behavior

The OFFLINE status of device should be ONLINE.

Relevant log output

I can ping device from ESPHome shell:

ping esp8266-ultrasonic-sensor
PING esp8266-ultrasonic-sensor (192.168.178.6) 56(84) bytes of data.
64 bytes from esp8266-ultrasonic-sensor.fritz.box (192.168.178.6): icmp_seq=1 ttl=254 time=3.77 ms
64 bytes from esp8266-ultrasonic-sensor.fritz.box (192.168.178.6): icmp_seq=2 ttl=254 time=5.60 ms
64 bytes from esp8266-ultrasonic-sensor.fritz.box (192.168.178.6): icmp_seq=3 ttl=254 time=3.68 ms

Screenshots