Connection failure of third-party

What can I do if my App account cannot connect /link with Google Home/Google Action/Alexa?

After connecting to Google Home, the device does not appear/sync in the Google Home App?

Why does my App account bind with Alexa skill successfully but failed to Google?

Why does "Incorrect username or password" display when I register an account and bind a skill/action?

Prompt when binding skills: “Google Action services are temporarily unavailable in the area where the account you have attempted to log in to is located”

When the App is bound to the Google Action, but the login page does not pop up, and it directly displays Linked?

Why can't I connect a Bluetooth mesh device to a third-party smart speaker?

How to handle the prompt "account does not exist" when binding Tmall Genie, Xiaodu, and other Chinese region skills to a account that data center is not in mainland China?