If you have a Floating license and ExtendSim has been working fine on Client devices, then all of the sudden Clients are no longer able to communicate with the License Manager on the Server, it might be because your Server was restarted some hours or days previously and the ISV port has changed.

The ISV port is used for communication between the License Manager and ExtendSim. Every time the Server gets restarted, the License Manager for the Floating license automatically restarts. And each time the License Manager restarts, it uses a different number for the ISV port.

Typically, this is not a problem because when the License Manager is initially activated, it picks a random, high number, unused ISV port, and that port is typically unblocked. But if that port is blocked you have to either unblock it both ways or set your own unblocked ISV port in the license file.

If ExtendSim stops working on a Client device, check the port number in the Status window of the RLSA on the Server. If that ISV port isn't already unblocked, set an ISV port in the license file (see the instructions on changing an ISV port in Frequently Asked Questions • Floating Licenses). The ISV port you set will always be used even if the License Manager restarts.