I just downloaded the MF923 manual. It is a indeed a router that utilizes a 3G/4G network.
What are you trying to do exactly? Is this for the control RRC? Where will the radio RRC be used, i.e. what
type of network? A radio RRC will not work on a 3G/4G network, BTW.
In order to get the RRC's to talk to each other, you must first set them up on the same network, or at least
connect them using an ethernet cable if they are set to factory default. Alternatively, use Microbit Setup
Manager and the USB cable to set the boxes to DHCP to be able to use a router like the MF923.
I don't know if you already have my networking checklist that walks you through the installation process. If
you want it, drop me a short mail to dj0qn (at) darc.de and I will send it to you.
73,
Mitch DJ0QN / k7DX