ESP Home addon does not see the sensors anymore

**Operating environment/Installation (Hass.io/Docker/pip/etc.):**

Hass.io version 0.109.6 in Docker
**ESP (ESP32/ESP8266, Board/Sonoff):**
ESP8266 - 2 boards - same behaviour

**Affected component:**
The ESP home addon does not see the sensors anymore. This happens on 2 identical sensors.

**Description of problem:**
The ESP home addon does not see the sensors anymore. I have checked the router - the sensors have static IP addresses. I have unplugged the sensors, replugged them - they show up in router under DHCP with static IP addresses, ESP does not see them. This is the error message from Show Logs:
`
INFO Reading configuration /config/esphome/bedroom_sensor.yaml...
INFO Starting log output from bedroom_sensor.local using esphome API
WARNING Error resolving IP address of bedroom_sensor.local. Is it connected to WiFi?
WARNING (If this error persists, please set a static IP address: https://esphome.io/components/wifi.html#manual-ips)
WARNING Initial connection failed. The ESP might not be connected to WiFi yet (Error resolving IP address: Error resolving address with mDNS: Did not respond. Maybe the device is offline., [Errno -2] Name or service not known). Re-Trying in 1 seconds
`
The sensors worked fine with this version of HA until last night - this morning the communication "died" .

**Problem-relevant YAML-configuration entries:**
```yaml
esphome:
name: bedroom_sensor
platform: ESP8266
board: nodemcuv2

wifi:
ssid: "xxxx"
password: "yyyy"

# Enable fallback hotspot (captive portal) in case wifi connection fails
ap:
ssid: "bedroom_sensor"
password: "zzzzzz"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:

ota:

i2c:
sda: D2
scl: D1
scan: True

sensor:
#WiFi Sensor for the NodeMCU
- platform: wifi_signal
name: "WiFi Signal Sensor"
update_interval: 60s
filters:
- lambda: |-
if (x <= -100) {
return 0;
} else if (x >= -50) {
return 100;
} else {
return (2 * (x + 100));
}
unit_of_measurement: "%"

#UpTime sensor for the NodeMCU
- platform: uptime
name: Uptime Sensor
filters:
- lambda: |-
return x / 3600;
unit_of_measurement: "Hours"

#Light Sensor:
- platform: bh1750
name: "Bedroom Luminosity"
address: 0x23
update_interval: 60s
icon: "mdi:brightness-6"

#Temperature Humidity and Pressure Sensor:
- platform: bme280
temperature:
name: "Bedroom Temperature"
oversampling: 16x
id: temperature
pressure:
name: "Bedroom Pressure"
humidity:
name: "Bedroom Humidity"
oversampling: 16x
id: humidity
address: 0x76
update_interval: 60s

#Air Quality Sensor:
- platform: ccs811
eco2:
name: "Bedroom eCO2 Value"
tvoc:
name: "Bedroom Total Volatile Organic Compound"
address: 0x5A
update_interval: 60s
baseline: 0x4481
temperature: temperature
humidity: humidity

#Text sensor for the NodeMCU
text_sensor:
- platform: version
name: "ESPHome Version"
- platform: wifi_info
ssid:
name: xxxxxx

#Reboot Switch for the NodeMCU
switch:
- platform: restart
name: "NodeMCU Restart"

```

**Logs (if applicable):**

```
PASTE DEBUG LOG HERE

```

**Additional information and things you've tried:**