GCM Unauthentication issue
I am using python-gcm package to implement push notification. All the things work correctly in my local server. However, when I deploy to DigitalOcean, this does not work, and return GCMAuthenticationException.
I am pretty sure that I am using the correct API key in my server code, and the IP I am using to whitelist in the GCM service for that key is exactly 18.104.22.168.
I have no idea why this happen. I followed exactly what this link says https://www.digitalocean.com/community/tutorials/how-to-create-a-server-to-send-push-notifications-with-gcm-to-android-devices-using-python