Main router (DG632) address 192.168.1.1 with DHCP enabled
IP range 192.168.1.100 -150
Turn DHCP off in DSL router and try setting IP address as 192.168.1.150
Make sure subnet is the same 255.255.255.0 on both routers
Make sure all Pcs and laptops are set to DHCP assigned IP addresses and are not static.