Unable to Connect to Server using Domain

Hello everyone,

I have set up a logmein client on a windows server 2016 standard that works under domain.
When i try to access it from me Logmein and i use the domain that the LogmeinControl panel says I receive error 1326 Login Failed.

This is what Logmein Control Panel says.
What should i use as a username . I have the correct password for the posuser account.

Thank you in advance.

SK