In order to restore a Sophos UTM configuration backup on a machine with similar specs, but a different IP address once the backup is installed the IP address of the old machine is on the new machine, which will not work.

NOTE:
I noticed when I was doing this on a Sophos UTM Manager, that somehow this resets itself every 10-30 seconds and I had trouble logging in and making the changes in the GUI. So I ping’d the new IP address and every time the ping stopped responding I repeated the steps below before I clicked anything on the GUI. I had to attempt it a couple of times, but got it done eventually.  And once you have saved the IP address change in the GUI it is permanent.

So log in from the console of the new machine and as root do this:

hostname -v ***
ip addr add dev eth0 X.x.x.x
ip link set up dev eth0
route add -net x.x.x.x netmask 255.255.255.0 dev eth0
route add default gw x.x.x.x dev eth0

this is only temporary until the next reboot. However you can now log in via the correct IP address to the admin interface of the new machine and make the necessary changes in the network settings and whatever else relevant.