SQL 14 AG go into read only when cluster is down, how? Looking at SQL 14 AG and trying to get this to work

https://blogs.technet.microsoft.com/dataplatforminsider/2013/06/27/alwayson-in-sql-server-2014-ctp1/

Increased availability of readable secondaries in multi-site environments

Readable secondary replicas now allow read workloads to run without any disruption even in the presence of lasting network failures or loss of quorum on the underlying Windows Server Failover Cluster. 

This is especially desirable in large-scale geo-distributed environments where network disconnections are not that unusual. This is depicted in the picture below, reports running on readable secondaries far from the main data center will continue running despite a network disconnection. Similarly, new reports started during the network disconnection will run. 

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We spent a good bit of time trying to get this to work with a two node clustered instance as primary and then a third node with a stand alone instance as the readable secondary. We can't find too much more info on it other than this link. Since it's from a CPT we're wondering if it's even in the software? Or what we're missing to get it to work. Any thoughts or help would be awesome.

Thanks
You have to set it up for all communication. If the WSFC is down, so is the AG and Listener. If you can directly access the secondary and it's set up, you can access it for readable.