it's in DCHP settings but as the OP says if you try to change it to 192.168.1.1 you get an error stating that the ip cannot be the same as the guest ip (even though no guest ip's are active)
however there is an answer (i just tried it and it works)
change the ip to 192.168.10.1 then click apply and close the browser (or tab) and wait for the superhub to reboot
now go back and change the ip to 192.168.1.1 and hey presto ... when you click apply no error and the ip will be changed when the s-hub has rebooted (after closing the browser/tab)
simples
