Retina MacBook Pro Running 10.13.5 Can't Connect to Windows Fileshare Servers We have several Windows-based file shares and one computer can't connect to them. By default, he should be able to use smb://server.name/share from Finder &gt; Go &gt; Connect to Server... and then get prompted for his username and password, but instead he gets an error almost immediately that says:

There was a problem connecting to the server &quot;server.name&quot;.
Check the server name or IP address, and then try again. If you continue to have problems, contact your system administrator.

Here's what we've tried so far in our troubleshooting:

Tried restarting the computer
Changed the server name to use the IP instead. No change in behavior
Confirmed that the server name and IP can be pinged
Tried using cifs:// instead of smb://. No change in behavior
Confirmed there aren't any saved credentials in Keychain Access that could be outdated
Confirmed we get the same error when trying to connect to different servers with different shares and using different accounts
I solved a similar problem on my computer a while ago.
I created a file /etc/nsmb.conf with the following contents:

[default]
signing_required=no


Be aware that you disable some security features with this procedure.
You can find more details in an apple support article.