MATLAB: Are MATLAB R2015b or newer Windows clients being denied a license, but R2015a or earlier works on the same machine

MATLAB

Our license manager was updated to v11.13.0.2 (R2015b).  After this update, clients on Windows machines are no longer able to checkout a license.  They receive a License Manager Error -39 despite having an IP address within the range included in the HOST_GROUP found in the options file.  For example:
HOST_GROUP info2 132.187.10.*
The machine's IP is 132.187.10.x
MATLAB R2015a starts up normally on this same machine.
Linux and Mac OS X clients are not affected. 

Best Answer

This error will occur if your network is using Network Address Translation to remap IP addresses. As of R2015b, MATLAB reports the real IP address to the license manager even if a NAT layer is in place. Previously, MATLAB always reported the NAT-translated IP.
There are two ways to resolve this issue. First, the options file can be updated to include the real IP addresses of the clients. However, it may be desirable for the license server to operate on a NAT-translated IP address instead of the client's actual IP address. For example, if using the EXCLUDE keyword in an options file to exclude all clients originating from behind a specific firewall. This would also be desirable in an environment which has a mix of MATLAB releases from both before and after R2015b, to ensure the IP addresses are being reported consistently across releases.
To always use the NAT-translated IP, set FNP_IP_ENV=1 on the MATLAB client. Setting this environment variable prevents the client resolving its own hostname to an IP address, which means the server instead obtains an IP address for the client from the socket connection.
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