After a few days of retrying and researching, and thanks to grawity_u1686 advice. I managed to solve the problem.

The problem is that in my AD Server, Active Directory Users and Computers > abc.local > Users. In the Account tab from the Properties of my linux user record (linux-wec), the User logon name holds the value of HTTP/linux-wec.abc.local, indicating that the principal used should be HTTP, not http. By recreating the keytab with HTTP principal, my NXLog managed to work normally.

Help appreciated with thanks.