Hi rwjharvard,
I hope your day and time is going well!
I suggest to add more details about your problem if you want get a better chance to have useful replies.
How do you think someone can reply to you just with your title discussion question?
Usually user should be able to login, if this never happen maybe your install can have some issue but without details I think will be hard for you get some useful replies.
What error do you get user that log in and the issue is same from different browser using also the incognito mode?
A screenshot of the error can be useful. Please be sure to remove every private info.
Did you check if the fail login generate some error log on /storage/logs?
What version of Flarum are you running and what version of PHP are this using?
From SSH paste here the result of the command: php flarum info can be useful because maybe you can have some extension installed that can be the cause of the issue you are facing. Have you tried to disable third part extension?
