We had originally configured our XP1 instance to communicate directly to a single SQL server and everything was working correctly. Before going live we update the SQL server to be part of a high availability cluster which changed the SQL server name.
Since the server was named differently we had to update all of our connection strings files to use the HA name. After doing that and restarting all of the services we are seeing an error in the xConnectCollection logs:
sitecore_xdb.collection.Shard1 is participating in an availability group and is currently not accessible for queries
This is the error you see when your connection strings are pointed directly at a server rather than the cluster name. I've verified that all of our connection strings are updated