M1-1100 and Nighthawk R7000 Connect together?

my sister has an m1 router/hotspot thru ATT and a Nighthawk R7000 Router. The Hotspot that my sister has doesnt have a Selection under setup that allowes Teather??? (For some reason??? Might be the software but it says most current ver. installed and it wont let me update to a newer ver even thought there is a new vers. of software?) I have the Exact same M1 Hotspot/router my sister has too but under setup MINE  has this "TEATHER Option" which shuts off wifi and enables the Router to accept the signal from the hotspot??? I was told that Bypass works the same as Teather But it DOES not :-(  I can Not get the M1 hotspot to work with the Nighthawk R7000 Router and have tried all that I was told IE (click Bypass and shut off DHCP and connet to Nighthawk R7000) Well yea that works 1 time then something happens when the power is turned off and modem is reset ot nighthawk R7000 power is reset??? I guess the Two Devices the M1 and the nighthawk R7000 have the Same Ip and that is the Problem??? I tried changing the Nighthawk R7000 Ip to what another artical said "Outside the range of the M1's IP address range  which is 192.168.1.20 to 192.168.1.99" I set the Nighthawk R7000 to Ip 192.168.1.100 and it Either doesnt find it or NO Internet??? I dont know much about Ips and don't have a clue what or how you set them can they be Any Random numbers? Or are there Certain Rules for the Ranges? 

What I want to know is

1) How Do I get the M1/Router and The NightHawk R7000 To Work Together, and IE "work Every time they are Turned off and then on Again Without Reprogramming them". 

2) How do I get the Software on the M1 Hotspot/Router to the Same Ver of Software as mine With the "Teather Option under the setup tab" 

Thanks Scottie D.