It must be noted that FTP and sFTP services operate on different ports and to force the usage on sFTP on your
dedicated server, you need to first block port 21 for incoming connections. This can be achieved by accessing your server through SSH with root for execution of the command as given below:
iptables –I INPUT –p tcp –dport 21 –j DROP
This must be repeated whenever you are restarting the firewall.
If you are logging to your account with help of sFTP and notice that any particular user’s home directory is not being accessed by users belonging to same group, then the issue can be resolved by enabling enhanced security option for the particular user.