[Samba] Connecting to samba server from android TV Box

[Alex]

Hi, I have one of those TV boxes that can be used to connect to a
samba server to play media files on a TV but I can't get it to
connect. Their support is nonresponsive. I'm a relatively experienced
Linux user and have samba working with another media box on the same
network.

The android media box with the problem is from Ninkbox and it's the N1
Max. The box says it's Android 9.0 using a RK3318 quad-core processor.
I can enter in the username and password for the share, and it appears
to login and display the list of available shares, but then returns
"mount fail" with no other indication as to what the problem could be.

Does anyone have any familiarity with these android boxes and how
samba should best be configured to work with them?

Here is my current samba config:
[global]
        workgroup = NETDEV
        server string = Samba Server Version %v
        netbios name = SAGE
        log file = /var/log/samba/log.%m
        log level = 4
        max log size = 500000
        security = user
        passdb backend = tdbsam
        unix password sync = yes
        lm announce = no
        lanman auth = yes
        ntlm auth = yes
        load printers = yes
        cups options = raw
[alex]
        comment = Alex Home
        path = /home/alex
        read only = no
        browseable = yes
        #valid users = dave
        guest ok = yes

The logs show that auth succeeded:

[2020/01/03 12:59:00.417475,  2]
../../source3/auth/auth.c:310(auth_check_ntlm_password)
  check_ntlm_password:  authentication for user [alex] -> [alex] ->
[alex] succeeded

Could it be a protocol incompatibility?  What more information can I
provide to further troubleshoot this?