Hi,
Can you please tell me where i can find all the blocked IP addresses and how to unblock one specific IP using the gui.
Thank you
Any IP is blocked only if you block it manually. It means that you should know where you have blocked them.
Default configration has no particular IPs blocked. Router in the default configuration has somo firewall rules which block trafic as is, not particular adresses. You can see all firewall rules with Winbox. The best tool ever to manage ROS 
Thank you for your explanation. The router has some rules setup to block unusual behavior.
And one client is block. I just need to unblock a specific IP And i just can’t find it using the WinBox.
Can somebody help me with this?
//Sorry for being such a noob
look at “ip-firewall- address lists”
the name of list is specified by your rules
We all have been “noobs” some day
There are many places where the client could blocked .. firewall is the simplest one. Open Winbox, choose IP, then Firewall and you will see firewall rules.
Could you explain a bit deeper what do you mean saying “IP is blocked”? Could this IP send data? do not recive traffic from some hosts? Is it server? Is it someone’s router? Anything what could help us. We can help you but we are not mentalists .. just more experienced users