Normally when you use router you will not know someone uses your internet. So it is reason to make your internet is slow, But there is no problem we will show you to know that who play your WiFi, you just follow to below way.
The First, install Advance IP Scanner but present this program uses with window only. Click here Download Advanced IP Scanner.
Click on scan and wait for 2 to 5 minutes, this is depend on number of WiFi using.
When finish the scan you will see information of user WiFi or internet such as Name, IP, Manufacture, Mac Address, but something you have to notice is manufacture because it is the device name of user, If you do not know, you can block IP address or mac address in router suddenly. But you make sure that all device which you scan were known who is those, you can check their device( smart phone, computer, mac OS…) so you will be right block and click here How to block someone cannot access internet on Router.
The way above can help you in order to close other to use your internet, so we hope that this way can help you to manage you internet.