Did you stop the server when you cleared those entries from the preferences.xml?
Are you on the same subnet when you’re trying to access the server through its local IP address?
I hope you know what you’re doing when placing your server in a DMZ… if not, that’s quite a gamble.
Your LAN having full access to the DMZ doesn’t mean they’re on the same subnet. You can only claim a server while being on the same subnet – if you’re not, you need at least to “simulate” that (e.g. by using a SSH tunnel → see related section in the server installation support article).
Solved,
i have the server in DMZ from years, so is configured well but i hare right, accessing the server is not the same to be on the same subnet so i have ssh port forwarder and than i was able to link my server to plex.tv.