Access router in double nat

[Helder Santos]

My setup is:

ROUTER#1 <-> ROUTER#2
ISP Modem/Router <-> MyOwnRouter
192.168.2.1 <-> 10.10.1.1

I was able to reach 192.168.2.1 from any machine connected to 10.10.1.1
But after a factory reset... I no longer able to reach the router#1
And I don't remember or find the configuration that will let me access again router#1

Thanks