Thanks Bushfiva.
I have read the routers instructions and it says the DHCP pool is xxx.xxx.0.100 to .199.
The router will accept addresses in the range XXX.XXX.0.1 to .253.
So, if I understand correctly, I can assign, say, XXX.XXX.0.210 to a device and this will be a static address as it is outside the DHCP pool.
The instructions imply that you can only use DHCP or not use DHCP but not a combination of both.
I will test it.