If your Mac can't use NTLM to connect to a Windows server

When using NLTM credentials to connect to a Windows server, your Mac might report that there was a problem connecting to the server.

macOS Mojave and earlier might not be able to use NTLM credentials to connect to CIFS or SMB1 shares on a server that has received Microsoft Windows Server updates from 11 June 2019 or later. After entering your user name and password, an alert says that there was a problem connecting to the server, and to check the server name or IP address and then try again.

If you're sure that your user name and password are correct, use any of these solutions to connect successfully. If you need help, contact your system administrator.

Connect to the server using Kerberos authentication, which requires that you use the DNS name of the share instead of its IP address.
If your Mac is using macOS Mojave, High Sierra, Sierra, El Capitan, or Yosemite, use SMB 2 or SMB 3 to connect to the server, such as by choosing Go > Connect to Server from the Finder menu bar, then entering an smb:// address for the server.
Enable server message block (SMB) signing on the server. On an SMB1 server, enabling signing can decrease performance.

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Published Date: August 09, 2019