The Upstash dashboard provides an example to connect to my Redis instance using a connection string:
const Redis = require("ioredis");
// Using *** to mask my credentials
let client = new Redis("redis://:***@fly-***.upstash.io:6379");
client.set('foo', 'bar');
However, this does not work (unable to connect).
Apparently, you need to use the IPV6 address to connect to the instance.
So I tried multiple combinations of x.internal and specifying the family to 6, but still no success.
What’s the actual connection string I should use to connect to my Redis instance?
Is there anything particular I need to do beforehand? 
Thanks for the guidance 
We just set this up with ioredis. Make sure to:
- Connect with IPv6 (you already mentioned this)
- Connect from within the Fly network. This is automatic from any Fly app, but in development you’ll need to activate a Wireguard tunnel on your machine or use the fly proxy command.
const Redis = require("ioredis");
const client = new Redis(
"redis://default:xxxxx@fly-xxxxx.upstash.io:6379",
{ family: 6 }
);
Thanks for the reply Elliot 
Connect with IPv6 (you already mentioned this)
How does one do that? Is simply passing in the family: 6 option enough? Do I need to use some sort of .internal address, or can I simply use the upstash.io url?

Using the family: 6 option with the Upstash URL works great. Thanks 