I regret to advise that there is no way to manually change the IP address on your Rocket Hub device. ☹️
A factory reset may cause it to reassign a new IP address, but it is not guaranteed and you could end up with the same IP. By doing this, you would also have to set up a new WiFi Name and Password as well.
FWIW, I did a factory reset after which, the DHCP fields were editable even though I didn't need them to be. I knew I had changed them to 192.168.2.1 sometime in the past but couldn't remember how. Looks like you get an edit window after a reset.
the default dhcp can be changed but you need to discomnect the hub from the cellular network first. you use the disconnect button on the main connection screen. then you can change the default 192.168.x.x to any ip of that range. then reconnect to the cellular network.
which model of rocket hub. the ZTE MF275R or the ZTE MF279T?