from a router noob perspective .not knowing what a setting does is somewhat of a hindrance to trying it .
i have the xtra technicolor TG582n router.
If i got into
Home > Home Network > Devices, and choose a device and delete it ..
Then i go to
Home > Home Network > Interfaces > WLAN:"name", and set it to "no new devices allowed " will it stop that or any other device from re/connecting ? and will it have any adverse effect on devises already connected ?