Why I get inconsistent connection with MySQL Workbench and Google Cloud SQL?

Question

I don't understand why I got inconsistent connection from my local MySQL Workbench to Google Cloud SQL.

Something, I can connect to my database the first time, sometimes, I need to try multiples times before getting a connection. Sadly, most of the time, it's not working.

Because I can rarely connect to the database, what kind of configuration can cause this problem?

Here's some infos:

• My application hosted on Google Compute Engine don't have any connection problem.
• My public IP (personnal computer) is added to the Authorised networks in my Google Cloud SQL instance. See: Enabling public IP and adding an authorized address
• I have added a Firewall rules to allow port 3306 in Google Cloud VPC network
• SSL is currently disable for the testing purpose
• I followed these instructions: How to connect to your Cloud SQL instance database with MySQL Workbench

Answer 1

For the benefit of future readers, the result of the comments above was:

The problem was that the client was alternating between two possible external IP addresses. One had been authorized to access Google Cloud, and the other one had not been authorized.

Enable all client IP addresses to connect, and that should fix it.