I have attempted to configure Google API restrictions for the Distance Matrix API.   I am using this API from my personal computer only at this time.   Eventually, I may also call this from an AWS EC2 instance.  I am using Python to connect to the API.  I have added my IP4 addresses in the format 00.000.000.00 and 00.000.000.00/32.  I have added IP6 in the format 0000:000::/64 and 0000:000::1.  I have also tried 0000:000:0000::/64 and 0000:000:0000::1.   My IP changes each time I connect to the internet via my cable provider.  I assume they use an IP range.   I cannot figure out how to specify this range other than the attempts above.   When I use the specific IP6 address (31 digits) from each login, the API works - until I log off.  That is not very scalable for repeated usage.  The error returned unless I enter the specific IP6 address is:

"error_message" : "This IP, site or mobile application is not authorized to use this API key. Request received from IP address 0000:000:0000:0000:0000:0000:0000:0000, with empty referer"
As per Google support, API restrictions do not support dynamic IP addresses.   The solution is to have a static IP.  Either restrict the address using HTTP or restrict the app by setting daily limits.
Configuring Google API Key Restrictions