when you reinstall the app, does it show RED on those devices?
you can try to cut off and then quickly resume them back.
also, if they still can’t get back on wifi. try shut down your phone see if it works. if still they can’t get back online after you shutdown your phone. ask them to do a reboot of their devices.
if after all those they still can’t get back online. there might be other netcut user that cutting them besides you alone .