@culerus  I think thats a bug. I want to do the same, but the same thing happening again and again

@culerus 

First please check the bandwidth control enable check box. Insert you ISP up and down speed and save(device will reboot). After that to create list entry, fill the input fields.
1. Insert the the ip of the desired device to restrict in first column, left second column empty.

2. Insert rang of port 1(fist column) to 65535 (second column).

3. Protocol => default

4. Priority => default

5. Upstream  : as per desired range   minumum(first column), maximum (second column)

6. Downstream  : as per desired range   minumum(first column), maximum (second column) 

Then save the newly create list.