[Samba] CIFS share disconnects on Linux client, but is still accessible via SMBCLIENT

[Lestrad]

Hello. My Wandboard running Arch Linux ARM mounts a cifs share hosted on 
a Windows 7 machine at boot. After a certain amount of time the 
connection to the share is lost. I can cd to the mount point directory, 
but when I run ls I get the error message: "cannot open directory '.': 
Host is down". If I unmount the mount directory and try to remount the 
share, I get a "mount error(2): No such file or directory" error.

However, I can still connect to the share using smbclient. And if I 
reboot the Linux box the share again mounts with no problem. But after a 
time it becomes inaccessible again.

I've tried several different things on the Windows machine, including 
enabling and disabling SMB v1 and trying all the possible settings for 
the NIC (Intel with the latest driver) and for Windows share 
permissions. But the problem must involve Linux, since the share remains 
available via smbclient and mounts with no problem when I reboot. I've 
updated samba to the latest version and enabled winbind. I'm not sure 
what else to try.

Any help would be appreciated. I can provide any information anyone 
might need.

TIA
Les

Arch Linux ARM version 5.7.2-1-ARCH
samba v 4.12.3
CIFS v 2.26
mount.cifs v 6.10