Hello,
Try to set up your routers as if they were the same as your main one, except turn the SPI firewall off under Security>Firewall>Firewall protection. Leave the WAN side on DHCP, but set different LAN IP (thus different subnet) than your main router. Example: main is 192.168.1.1 mask 255.255.255.0 second router from main LAN is 192.168.2.1 mask 255.255.255.0 and third is 192.168.3.1 mask 255.255.255.0 . Third and second behind main router could have the same LAN subnet, but it's easier to make difference while you're working on a resolution to a specific problem. Of course you have to configure the main one to give hotspot on LAN and leave the hotspot on 2nd and 3rd routers turned off.
LEt us know, how it goes.
Best Regards,
Steve Hars,
Helpdesk @ hotpotsystem.com