If you don't specifically add the TCP/IP port number to the license file it can change. When checking the network license usage status with JTB FlexReport you can find this error for example in the HTML report:
Error getting status: Cannot connect to license server system. (-15,10:10061 "WinSock: Connection refused")
Typically this does not happen if you have one license file on the server but if you have several vendor daemons the port number can be switched depending on what order the services are started. This can result in that the data stops being logged to the database and that the HTML reports does not show the current usage. It’s recommended that you enter the port to the license file it it’s not already there. To find the current used port you can use lmtools.exe and check for it using Perform Status Enquiry. See How to find the port used by a FlexNet license service.
The format of the SERVER line in the license file is:
SERVER host hostid [port]
SERVER my_server 17007ea8 27000
SERVER my_server 17007ea8 TCP:27000
It is recommended to use a port number in this range: 27000-27009.
Use lmtools.exe and stop and start the service.
If you for some reason would want to change the port used by the vendor daemon it is also possible to do in the license file. But it is strongly recommended to leave it as it is.
For example in an Autodesk license file it can look like this, just change 2080:
VENDOR adskflex port=2080