Admin Panel -More Settings - LAN IP section
If I change the LAN IP of the Router, say to 10.0.0.138, would that also change the first 3 sections of the Start IP Address & End IP Address to 10.0.0 or would they stay as standard 192.168.1 ??

Would be easy if they change, but if they stay as per original 192.168.1 then I will go into Luci and change as per your advice.