I always have an issue similar to this. Most mornings, mine and my wives will complain, that there's no Internet access via Wi-Fi. If I open the GL.iNet app it will show, that there's no Internet access. If I reboot the router, it will work again without problems. I've also noticed, that if I try to open any website on a PC connected via Ethernet, the problems will also be gone.
My setup is simple: a fiber modem from my provider connected to the WAN port on the Flint 2. The WAN port has the MAC address of the previous router, so that it gets a public IP assigned. Phones connect via Wi-Fi, PCs via Ethernet.
