nighthawk lte mobile hot spot router

The default gateway IP address of the MR1100 is 192.168.1.1 so it's likely that both your devices have the same IP address. You need to change one of them to avoid this clash. Pick a number that is outside the DHCP address range of both devices and also that doesn't clash with the address of any other router in your network. For example, you could set one MR1100 to 192.168.1.2. If you are using DHCP on both devices or on another router in your network, it's a good idea to set their DHCP ranges so that they don't overlap. For example, the DHCP start address on the one MR1100 could be 192.168.1.10 and the end address could be 192.168.1.130. Then the start address on the other could be 192.168.1.131 and the end address could be 192.168.1.250.

I've tried to write an extensive answer but for some reason it doesn't post. So I'll give you a quick suggestion - change the default gateway IP address of one of the MR1100s so that they aren't both set to 192.168.1.1, e.g. 192.168.1.2. Remember that once you've changed the address, you will have to use the new address to access its interface using a browser.