“Kill Switch” has been changed to “Block Non-VPN Traffic” in Firmware 4.0 and behaves like before. This is because GL.iNet’s previous Kill Switch is intended to block traffic even if you do not Enable VPN at all, which is to force you to use VPN even to access Internet. This is different from commercial VPN providers’ definition of Kill Switch, so “Block Non-VPN Traffic” may be a better term for how GL.iNet actually works.
If you use VPN app on client devices, then turn off “Block Non-VPN Traffic” and turn on Kill Switch in the app.
I do not work for and I do not have formal association with GL.iNet