hello,
two things to check
1. make sure you controled right device. you can verify that by look at your phone’s IP address and make sure locate the same IP address inside netCut. sometimes those phones have same name. only IP or MAC address is unique.
2.once you confirmed the right IP address, when you do block activity , keep the blocking on , as some of the activity use buffering, if the phone you test already have youtube video viewing, the phone does not need internet connection TILE it need to further BUFFER, eg: another 5 to 10 minutes, the block will only start to work when the phone start to make a request to internet. to test that, you can make your phone switch to browse another new video when blocking is ON already.
If it still can’t block, verify by click on the WIFI icon of the device to 100% shut off it’s internet , see if it works, if it working, that proof the netCut be able to control it’s speed. if can’t CUT off 100%. then your PC (windows) might have installed certain VPN or certain firewall that turned on your PC into a proxy, this case, it conflicts with netCut. you have to switch to a difference PC without those app co-exist.