This should bring you to the same log in page, but redirect you to the server setup.
The default server name is LocalHostLocalDomain, change this to PlexMS. Now the address [//plexms.amahi.net //PlexMS.Amahi.Net] should bring you to the server page (with player too).
Also, visiting your Dynamic DNS name followed by port 32400 (example.yourhda.com:32400) will bring you to a player from anywhere on the internet. Port forwarding is required at your router's firewall.