Your member server does not map IDs to usernames any more. Additionally authentication might fail.
You notice the following output from wbinfo:
root@ucs:~# wbinfo -t checking the trust secret for domain DOMAIN via RPC calls failed wbcCheckTrustCredentials(DOMAIN): error code was NT_STATUS_DOMAIN_CONTROLLER_NOT_FOUND (0xc0000233) failed to call wbcCheckTrustCredentials: WBC_ERR_AUTH_ERROR Could not check secret [...]
The server was recently upgraded from UCS 4.1 to current version.
A bug in UCS 4.1 lead to a non updated machine password.
Although the server in question was on UCS 4.3 it was likely the attribute “sambaPwdLastSet” was not updated after machine password rotation as the server has been on UCS 4.1 a while.
A re-join of the member server solved the issue. A second option would be to force the password change.