I'm trying to set up a imaging environment. The idea is to use DISM to apply WIM images (Windows 10 Pro) over the network.
I am able to boot into Windows 10 PE. I have network connectivity via DHCP.
When I try to map the network share using net use i: \\server\share I get: 
System error 58 has occurred. 
The specified server cannot perform the requested operation.
If I try to map it with net use i: \\server\share /user:user password where user is a system user, it works. 
The share is is completely public. I am able to map the share with no credentials on 4 other Windows machines. (2x Win7, 2x Win8).
The server is Ubuntu 14.04 running Samba. 4.3.9-Ubuntu.
My /etc/samba/smb.conf looks like this:
[global]
    workgroup = WORKGROUP
    security = user
    server string = Imaging Server
    dns proxy = no
    follow symlinks = yes
    wide links = yes
    unix extensions = no
    log file = /var/log/samba/log.%m
    max log size = 1000
    guest account = nobody
    encrypt passwords = true
    map to guest = bad user
[share]
    comment = images
    path = /share
    browsable = yes
    guest only = yes
    read only = no
    writable = yes
    public = yes
    create mask = 0664
    directory mask = 0775
/share is owned by nobody:nogroup 
Any ideas would be appreciated.