We're moving all users and our server from FM 14 to 16.
For some users, the transition is seamless: they can launch FMP 16 and see the test file on the new FMS 16 host.
For other users—on the same LAN, running the same MacOS 10.11.6—they can see the new host in Launch Center but in place of the test file they see "Connection Failed."
I've confirmed port 5003 is open on the host computer when tried from these computers that can't open the test file.
What else should I try to help these users connect to new FMS 16 hosted files?