I have a web app on Google Cloud - App engine, using a custom domain and a custom SSL (both on namecheap). As soon as I activate Cloudflare, I get 522 error with spikes in the response time of the website in some locations.
I went through this guide:
but it did not solve my issue.
Some additional info:
1 - Response time spikes disappear as soon as I pause Cloudflare, so this cannot be a temporary server problem or a load problem with App Engine;
2 - I have added all the Cloudflare IP ranges to the App Engine firewall:
I have an ‘allow’ rule for each one of them. I have checked that list multiple times to make sure I did not miss any of them.
Any suggestions on additional steps? Thank you.