AppEngine Firewall does not allow access from other AppEngine Flexible IPs

[Daniel]

I set the Firewall rules according to this:

https://cloud.google.com/appengine/docs/standard/ruby/creating-firewalls

Allow 0.1.0.40 

Allow 10.0.0.1

Allow 10.1.0.41

Deny *

The default is `Deny` 

I can't connect from other AppEngine Flexible services to this service.

[David (Cloud Platform Support)]

Hello,

I see you mentioned apps are running in App Engine flexible and the document you are using is meant for App Engine standard. Please refer to this document which is intended for App Engine flexible. However, I do see you have the relevant IP addresses for flexible added to your firewall rules 0.1.0.40 and 10.0.0.1.

How are you trying to communicate between these two services? The simplest approach for communicating with your App Engine service is to send targeted HTTP requests. Please take a look at our documentation about this in order to learn more.