No. You can activate licenses manually from another computer with internet access using Manual Installation page. The Hardware ID can be found if you launch the License Server with the "run" command.
Host: services.keentools.io, port: 443. It happens when a license is being installed and when a running instance of License Server is checking installed licenses from time to time.
This may happen with licenses of a wrong type. Only floating licenses work with License Server.
Check there are no firewalls between the user's machine and the machine with the license server. The default port used by License Server is 7069.
Please, check there are no other processes using that port on the machine where License Server is being run.
You can redirect stdout to the License Server executable, i.e.
"cat licenses.txt | ./KeenToolsLicenseServer install"
"echo 'license1 license2 license3 ...' | ./KeenToolsLicenseServer install"
The licenses are being read during the startup, so you need to restart the existing License Server process to make newly installed licenses available for users.
There's no difference if you know how to use the OS of your choice as a server.