thank you valens ... i have another question, can we register or put our client ip address in some kind of ip table in the router? FYI, i use mikrotik OS 2.8.28. Thank you btw, i already did what u've suggested, but the ip i want to drop or reject is still in my firewall connections table, they stil...

i'm a newbie here, i have some clients with their own static IP address range 192.168.0.0/24. If they change their IP to another number, how to make them disconnect to the router. Or in other word, how can we drop unwanted client IP address on our router local interface? thanks