I have used this guide Google Assistant - Home Assistant to setup access to my HA from Google Assistant.
I use an ASUS router and have used their DDNS service with name my-domain.asuscomm.com.
I used the Let’s Encrypt option to create cert.pem & key.pem files and placed them in /ssl.
I setup my router to forward ports 8123 and 443 to the ip address of my HA server.
I added these lines to my configuration.yaml:
…
http:
ssl_certificate: /ssl/cert.pem
ssl_key: /ssl/key.pem
…
I set up HA System>Network thus:
Home Assistant URL: https://my-domain.asuscomm.com:8123
Local network: https://my-domain.asuscomm.com:8123
I then tested and proved browser access to HA from my local & remote networks using this URL:
https://my-domain.asuscomm.com:8123
I also used this URl in the Home Assistant Companion app and again successfully tested local and remote access.
All good so far.
I then proceeded to set up Google.
Here is a summary of the integration configuration:
Integration name: HA
Device type: everything
Client ID: https://oauth-redirect.googleusercontent.com/r/my-project-id
Client secret: random string
Authorization URL: https://my-domain.asuscomm.com:8123/auth/authorize
Token URL: https://my-domain.asuscomm.com:8123/auth/token
Fulfillment URL: https://my-domain.asuscomm.com:8123/api/google_assistant
Scope: email
Scope: name
I then setup the credentials. Here is the resultant SERVICE_ACCOUNT.json, placed in /configuration
…
{
“type”: “service_account”,
“project_id”: “my-project-id”,
“private_key_id”: “my-key-id”,
“private_key”: “-----BEGIN PRIVATE KEY-----\nmy-private-key\n-----END PRIVATE KEY-----\n”,
“client_email”: “[email protected]”,
“client_id”: “my-id”,
“auth_uri”: “https://accounts.google.com/o/oauth2/auth”,
“token_uri”: “https://oauth2.googleapis.com/token”,
“auth_provider_x509_cert_url”: “https://www.googleapis.com/oauth2/v1/certs”,
“client_x509_cert_url”: “https://www.googleapis.com/robot/v1/metadata/x509/geronimo%40my-project-id.iam.gserviceaccount.com”,
“universe_domain”: “googleapis.com”
}
…
I added these lines to my configuration.yaml:
…
google_assistant:
project_id: my-project-id
service_account: !include SERVICE_ACCOUNT.json
report_state: true
exposed_domains:
- switch
- light
entity_config:
light.lamp_bed1:
name: Test lamp
aliases:
- Lamp test
room: Bedroom 1
…
From my phone I then opened the Google Home app and did the required configuration.
All went well and I was asked to provide credentials to log into HA, but I got the response:
Could not reach my-integration. Please try again.
Here is what the HA log shows:
2026-01-24 07:26:09.669 WARNING (MainThread) [homeassistant.components.http.ban] Login attempt or request with invalid authentication from rate-limited-proxy-108-177-77-53.google.com (108.177.77.53). Requested URL: ‘/auth/token’. (OpenAuth)
Could anyome please guide me on what might be the issue?