Matlab 2016a has a known bug + fix, 2016a does not work with redundant network license servers.
If this update is installed, no action below is required.
Another solution is to just replace the contents of your license server pointer method with the main server ONLY, deleting the contents of the redundant servers.
EDIT: THIS METHOD DOES NOT ALLOW SIMULINK CHECKOUTS, in order to permit simulink checkouts, the patch must me installed.
For example, network.lic contents for a triad server:
SERVER hostName1 hostID1 port PRIMARY_IS_MASTER
SERVER hostName2 hostID2 port
SERVER hostName3 hostID3 port
USE_SERVER
Should be replaced with:
SERVER hostName1 hostID1 port
USE_SERVER
network.lic in the licenses folder of the matlab 2016a installation location is the 5th and final place checked for a license.
The previous 4 are described in this article:
For -c starutp arguments, environment variables, and registry keys, the port@host syntax must also reflect only the main server.
E.g. a startup command on windows must be:
matlab -c "port@hostName1"
NOT:
matlab -c "port@hostName1,port@hostName2,port@hostName3"
On linux, a semicolon is used instead of a comma to differentiate redundant servers.