I don't think Huawei HG8245H has the bandwidth control feature. So you can't limit bandwidth of your WiFi users. But you can use an app called netcut to cut the internet access to your WiFi clients.
To use this method you need a rooted Android phone or a windows pc or laptop. In your android phone launch play store. Search for NetCut (the app icon is a scissor). Install the app and open it. Grant the app root permission when asked. The app will load info about all users connected to you WiFi. It'll show the symbol of the manufacturer of the connected devices. In case it does not show any symbol or there are more than 2 devices from the same manufacturer (like two phones of Samsung connected), you need to know the Mac address of the device whose internet speed you want to alter. Once you have determined the device you can either completely stop the device from accessing the internet or you can adjust the speed of the device’s internet connectivity. Just press the WiFi iconed button near the name of the device. Slide the slider to adjust the speed. The minimum position of slider will completely stop internet and the WiFi icon near the device name will become completely red. This method also ensures that the device whose speed you want to limit, does not get disconnected from WiFi. Just the device's user won't be able to open any webpage or access internet. To resume the connection just tap the name again.
NetCut for android : NetCut - Android Apps on Google Play
NetCut for Windows : Free Netcut for Android , NetCut and NetCut-defender downloads
P.S. To alter the speed you'll require pro membership. Without pro membership you can only stop the internet access. You can't alter the speed as per ur wish.