CIFS share authentication failing

Greetings.
We use a VNX5500. And We have a sudden problem in our environment. All of Unix devices and other non-windows equipement lost access to the filesystems shared by CIFS share. When we trying to mount then again we get the
Permission Denied -13 error. Beside that, the Windows devices cannot browse CIFS server using IP. When we try to browse using ip a auth prompt is popped and credentials are not accepted. They were working until  4 days ago. The desconnection hapenned simultaneous for all devices.
Our CIFS server is configured over a Virtual Data Mover and using ACtive Direcory. I run a server_checkup server_2 -test CIFS -full comand and receive the following output:


--------------------------------------------
Error 13160939579: server_2 : PingDC failure: The compname 'CIFSSERVERNAME' could not successfully contact the DC 'DCNAME'. Failed to access the pipe NETLOGON at step Open NETLOGON Secure Channel: DC NETLOGON pipe failure:Access denied
--> Check domain or Domain Controller access policies. For NetBIOS servers, ensure that 'allow pre-Windows 2000 computers to use this account' checkbox is selected when joining the server to the Windows 2000 domain.

-------------------------

And

----------------------

Warning 86171451396: server_2 : There is a Service Principal Name (SPN) mismatch possible for server 'CifsServernameFQDN', where NTLM authentication was used instead of Kerberos for share mounts. This could result in an increased load on the domain controller and loss of access when the domain controller is not available. Incoming clients connecting to server 'CifsServerFQDN' have use the server name 'CifsServerOldFQDN'. This mismatch has occurred 0 times since the last event logging, and 1179 times since the last Data Mover reboot.
--> Use the server_cifs command with the -setspn option to list the SPNs for the specified server, then use the command to add or delete SPNs until there is no longer a mismatch. If the mismatch is expected, the cifs.spnCheck parameter should be used to disable the mismatch detection and event logging.


In addition, I realized that the last Update of my Cifs server in my DNS Server was 4 days ago. We don't have vendor support anymore. So, any suggestion to detect the problem is welcome.

I'm not a Native English Speaker. So if anithing is not clear, please let me know

Thanks in Advance