share connection to create two independent networks

[bruinsrme]

My son moved back in and I want to split off him from my network.
Please refer to the picture.

I am having conflicts.
Router is set to
10.1.1.1

Default gateway is the cable company provided addresses

Network 1
10.1.2.1
DHCP
Default gate way 10.1.1.1

Guest Network
172.1.1.1
Default Gateway 10.1.1.1

Network 2
10.1.3..1
DHCP
Default gateway 10.1.1.1

I can't get the two networks talking at the same time.
Can the SSID be different for the network 2 and 3?
What modes should each router be set to?
Any other info wuld be gratly appreciated/

thank you