Thank you for your post.
This does usually mean that another computer has your license installed on it or (as it seems you've found) your computer has multiple IP addresses. If you have both Ethernet and WiFi enabled, you might disable WiFi. This can also occur if your computer is given an IPv6 address along with it's IPv4 address.
Having both WiFi and Ethernet enabled is a common office-live scenario on a laptop computer.
Even with both network devices enabled, it is still one copy of FMP on one computer - and one license is required, not two. The EULA does not make any restriction regarding the number of IP addresses of the machine on which FMP is installed. There should not be a license conflict because the machine has more than one IP address. Please elaborate.
I apologize if I made it seem to be expected behavior. I just meant for it to be a troubleshooting step that could resolve or at least show us where the issue lies, if a second machine is not using the license.
Basically, the Network or FileMaker Server is seeing the same license key coming from two different IP Addresses. It may interpret these two different IP addresses as two different machines. At least, I have seen this happen in the past.