Intermittent Issues Accessing SMB Shares from Windows 10

[Yangorang]

I'm not sure exactly when these issues started for me but it has been happening on both FreeNAS 11.3 and TrueNAS Core 12 in recent months.
I typically access my shares from one of two Windows 10 PC clients. Both are on the latest update and I'm logged into both with the same Windows user which has permissions to the shares.
On occasion after the PC is sitting around on for a while I will get the "Windows cannot access \\freenas\share" error when trying to access my shares. After simply restarting the PC everything will start working again.

In log.smbd I see the following messages:

[2020/11/28 15:06:17.216159, 1] ../../source3/smbd/service.c:369(create_connection_session_info)
create_connection_session_info: guest user (from session setup) not permitted to access this share (BACKUP)
[2020/11/28 15:06:17.216293, 1] ../../source3/smbd/service.c:557(make_connection_snum)
create_connection_session_info failed: NT_STATUS_ACCESS_DENIED

Any ideas as to what is causing this? It appears as if the Windows client is trying to access the share with guest credentials rather than passing my windows acct credentials, but it seems odd to me that this happens intermittently and it works again after a simple restart.
I tried to set the AllowInsecureGuestAuth reg key to 0 on both PCs but that didn't seem to do anything. I'm not too experienced with FreeNAS and could use some guidance as far as what debug steps are needed for this issue.

My smb4.conf has only the following:

# SMB.CONF(5) The configuration file for the Samba suite
# $FreeBSD$
#
[global]
dns proxy = No
aio max threads = 2
max log size = 51200
load printers = No
printing = bsd
disable spoolss = Yes
dos filemode = Yes
kernel change notify = No
directory name cache size = 0
nsupdate command = /usr/local/bin/samba-nsupdate -g
unix charset = UTF-8
log level = 2 auth_json_audit:3@/var/log/samba4/auth_audit.log
obey pam restrictions = False
enable web service discovery = True
username map = /usr/local/etc/smbusername.map
username map cache time = 60
logging = file
server min protocol = SMB2_02
unix extensions = No
restrict anonymous = 2
server string = FreeNAS Server
bind interfaces only = Yes
netbios name = freenas
netbios aliases =
server role = standalone
workgroup = ZHOU
idmap config *: backend = tdb
idmap config *: range = 90000001-100000000
registry shares = yes
include = registry