I assume you are using the password you setup in the install? if that is still not working you will need to plug in a monitor, keyboard and mouse to the NAS and you will have the ability to change the truenas_admin password
The deck shows my hexOS server as unavailable and won't connect. I can see the server is online, shares are up and running, and I can log into the trueNAS web ui directly.
I did have tailscale on at first, but I have turned that off and tried everything short of restarting hexOS.