Something needs to provide routing between subnets or you need to change the subnet mask on the router interface, DHCP scope and clients to 255.255.254.0? What type of router? If Cisco, you can apply the 192.168.11.0/24 subnet as a secondary address to the LAN interface.
int fa0/1
ip address 192.168.11.1 255.255.255.0 secondary