I do something like this, but I use a different method. I simply use mwan3 with a separate USB-WiFi adapter exclusively for this use. That way, my main WiFi ra

I do something like this, but I use a different method. I simply use mwan3 with a separate USB-WiFi adapter exclusively for this use. That way, my main WiFi radios are not negatively affected when I activate the hotspot. I already have my phone configured as a hotspot for when I travel, and I was already using mwan3 on my router already, so setting it up this way was easy and just made sense. mwan3 is configured to use the regular wired connection whenever possible, but if it goes down, then it switches over to the hotspot radio. Both conditions must be met: Hotspot is on, and main internet is down. If my internet is down, all I have to do is press a button of two on my phone to turn on the hotspot and everything else happens automatically. Another advantage of having a separate and different WAN interface is that I have ACLs on this interface which prohibit certain high-intensity types of traffic that I don't want transiting the hotspot. I just have to remember to put a fan on the phone when I do this. It gets hot.