|Maybe you need to use a crossover cable then when interconnecting the two router's.|
The rule is, "always use a crossover cable when connecting like devices" This is why when you go straight from one PC to another, you have to use a crossover. However, most modern switches are auto MDIX capable. Which means they'll automatically detect whether a cable is a crossover or regular patch cable and adjust for them automatically. If both devices are auto MDIX, then you can use a regular patch cable although I always use a crossover regardless.
You may have a router that's not auto MDIX capable.
I can't think of any other reason the cable would work from router 1 to your PC but not from router 1 to router 2
Oh and just FYI, a SOHO router's LAN ports are essentially "switch" port.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.