Cloud SQL Proxy: "couldn't connect ... dial tcp ...:3307: getsockopt: connection timed out"
The proxy intentionally dials the Cloud SQL instance on port 3307 (local clients still use 3306; 3307 isolates proxy traffic on the instance side), so your firewall/VPC must allow egress from the proxy host to the instance IP on port 3307. Per the maintainer's closing summary, this error always means the proxy has no …
Problem outcome: unknown