External authentication is not working for my FileMaker 16 Server, running on MacOS 10.12.5.
System Preferences --> Users & Groups --> Login Options shows a green light next to the AD server.
In the Terminal, if I type "id [username]" for a user in the external AD directory, I see the expected list of groups that the user is in, including groups that should have access to the database.
On the server console webpage, under Database Server / Security, I have the Client Authentication dropdown set to "Filemaker and external server accounts".
Firewall is totally disabled on the server (for testing purposes; disabling the firewall didn't solve the problem).
In my database, I have several externally authenticated accounts set up.
Client computers (MacOS 10.12.5 running FMP 16, 15, or 14; I tried all three) can connect to the hosted database with a Filemaker account (local to the database), but not with an externally authenticated account.
What am I missing?