I have setup a windows failover cluster on two servers on Windows 2012R2 with a file share for quorum. On top of this I have deployed SQL Server 2016 Always On Configuration and if I manually fail over between the two servers everything works perfectly.
If I use the automated fail over and then switch one of the servers off I get the following error message in the logs
Cluster IP address resource 'LabDBs_10.13.2.51' cannot be brought online because a duplicate IP address '10.13.2.51' was detected on the network. Please ensure all IP addresses are unique.
If I stop the server role and then start it again the role comes backup without any issue so it seems like when the role is running the IP is not released but when I stop and start the role the IP is released and then it is reassigned to the second server other server.