Access Denied on cifs mount

Good evening,

I've got a LibreELEC kodi box on a Raspberry Pi 3b+ up and running.

LibreELEC (official): 8.2.5 (RPi2.arm)

The problem: I've connected USB drives directly to the Pi. I'd like to access the drives from other devices on my network.

I created a /storage/.config/samba.conf

# samba.conf v4 (do not remove)

# This configuration file allows you to customize the samba shares
# available from your machine

[UsbDrives]
path = /media
available = yes
browseable = yes
public = yes
writeable = yes

Nothing I've tried works reliably to connect to this from my Mint Linux box.

I tried the file browser and get timeout errors.

Now I'm trying using CIFS mounts but can't even authenticate:

sudo mount -v -t cifs //192.168.1.109/UsbDrives /mnt/htpc -o username=kodi,password=libreelec,domain=workgroup,vers=3

dmesg returns login failures:

[693753.365082] Status code returned 0xc000006d STATUS_LOGON_FAILURE
[693753.365095] CIFS VFS: Send error in SessSetup = -13
[693753.365112] CIFS VFS: cifs_mount failed w/return code = -13

I've tried every combination of password and username I can imagine, plus the wiki's specified default of "libreelec"

Any suggestions? (Is moving to NFS possible?)