tether mifi 8800l through usb to RTN66U

[gamewarden3006]

So I am trying to tether my Mifi 8800L device through the USB port of my RT-N66U. Trying to set this us as Dual wan to Combine the speed of the Mifo and my Wired connection. I can get it to work just fine with my Pixel 3 Phone but I can not get the Mifi to work. It keeps giving me an IP conflict message. I have tried changing the IP address of it to no avail. I have read on several forums that this Mifi works with Asus routers but no luck here. Am I missing something?

I am running Merlin 380.70 Firmware