I have the same problem with the synchronization of google calendar as Hannes Hörting even I'm using our public IP for creating the API credentials. The router is forwarding the port 8069. Everything is working fine and It is possible to connect from outside to our local odoo server.
The first try was with the following URI: http://121.xxx.xxx.xxx:8069/google_account/authentication
For the second try I configured DNS of a domain name I had left to our server. After 24 hours the DNS was working and I used the following URI for the API credentials: http://ourdomain.ch:8069/google_account/authentication
After pressing the synchro button I get allways the same error:
400. That’s an error.
device_id and device_name are required for private IP: http://10.0.0.5:8069/google_account/authentication
Why is still used my local IP? What is wrong and where should I change this settings?
Thanks for help.