Looking at the trace we can see the kernel tries to mount with SMB3 and the server doesn't seem to support that. So either: - fix samba configuration by putting "max protocol = SMB3" if that is supported (consult man smb.conf for list of choices for you samba version). - force kernel to use SMB2 or SMB1. You need to put vers=2.1 or if that fails vers=1.0 in your mount options.