wireless access point - How to create/configure a secondary WiFi network with a secondary router connected to a switch?

I've got a router far from the room I use as an office. I've got a Gigabit Ethernet cable from there that goes to a switch and then to several computers/devices. Now I'd like to have a secondary WiFi network for my office.

I've connected the router to the switch, deleted its WAN settings, and configured it as an Access Point. The wireless network is seen -- for example, by my laptop -- but there's no Internet access.

I guess I must add some routing, but I've tried and didn't succeed. The control panel of this router (a Comtrend AR-5381u) on this part is as follows:

But I've messed up with the prefix, and I'm not even sure that's the part I must modify.

To clarify:

• Main Router: 192.168.1.1, WiFi SSID "House", DHCP enabled
  
  (192.168.1.33-99)


• Secondary Router: 192.168.1.2, WiFi SSID "Office", DHCP enabled
  (192.168.1.25-32)

What am I missing?