ESPHome node not connecting to shelly 1PM Gen4 configured as range extender

Hey there,

I have an ESP8266 controlling my irrigation system with 3 zones. It has very poor wifi reception, so I added a shelly 1PM gen4 nearby and configured it to be a range extender (wifi is configured, signal weak but stable, ap with ssid and pw configured, option range extender enabled).
Somehow my ESPHome node does not connect to the shelly. It always connects to my IoT wifi (at about -90db), not the IoT-extender. Is there a configuration problem on my end? Can someone please help?

esphome:
  name: bewasserung
  friendly_name: Bewässerung

esp8266:
  board: nodemcuv2

# Enable logging
logger:

# Enable Home Assistant API
api:
  encryption:
    key: "XXXX"

ota:
  - platform: esphome
    password: "XXXX"

wifi:
  networks:
    - ssid: !secret wifi2_ssid
      password: !secret wifi2_password
      priority: 10
    - ssid: !secret wifi_ssid
      password: !secret wifi_password
  
  min_auth_mode: WPA2

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Bewasserung Fallback Hotspot"
    password: "XXXX"

captive_portal:
    
switch:
  - platform: gpio
    pin: D1
    name: "Hügel"
    icon: mdi:thermostat
    id: "Z1"
  - platform: gpio
    pin: D2
    name: "Wassersteckdose"
    icon: mdi:thermostat
    id: "Z2"
  - platform: gpio
    pin: D5
    name: "Beet"
    icon: mdi:thermostat
    id: "Z3"
[21:12:11.984][C][wifi:1526]: WiFi:
[21:12:11.984][C][wifi:1526]:   Local MAC: 44:17:93:0D:B5:49
[21:12:11.984][C][wifi:1526]:   Connected: YES
[21:12:11.984][C][wifi:1237]:   IP Address: 192.168.39.3
[21:12:12.003][C][wifi:1248]:   SSID: [redacted]
[21:12:12.003][C][wifi:1248]:   BSSID: [redacted]
[21:12:12.003][C][wifi:1248]:   Hostname: 'bewasserung'
[21:12:12.003][C][wifi:1248]:   Signal strength: -95 dB ▂▄▆█
[21:12:12.003][C][wifi:1248]:   Channel: 6
[21:12:12.003][C][wifi:1248]:   Subnet: 255.255.254.0
[21:12:12.003][C][wifi:1248]:   Gateway: 192.168.38.1
[21:12:12.003][C][wifi:1248]:   DNS1: 192.168.38.7
[21:12:12.003][C][wifi:1248]:   DNS2: 0.0.0.0

Regards,
Anduril