more /etc/redhat-release
CentOS Linux release 7.5.1804 (Core)

uname -r
3.10.0-862.2.3.el7.x86_64

sestatus
SELinux status:                 disabled

firewall-cmd --zone=public --list-all |grep samba
        rule family="ipv4" source address="XXX.YYY.ZZ.1/24" service name="samba" log prefix="samba" accept

rpm -qa |grep samba-4
samba-4.7.1-6.el7.x86_64

id
uid=1001(testuser) gid=1000(testgroup) groups=1000(testgroup),100(users)

[global]
# ...usual staff like master, group, netbios-name...
        load printers = no
        printing = cups
        veto files = /*.[mM][pP]3

        interfaces = lo enp3s0f0
        security = user
[TestUser]
        path = /home/testuser
        writeable = yes
        browseable = yes
        read only = no
        valid users = testuser
        write list = testuser
        read list = testuser
        printable = no
        create mask = 0640
        directory mask = 710
        force create mode = 0640
        force directory mode = 0710
        inherit acls = no
        inherit permissions = no

[TestUser]
        path = /home/testuser
        browsable =yes
        writable = yes
        guest ok = yes

chown -R testuser:testgroup /home/testuser/
chmod -R 700 /home/testuser/