Network configuration with 2 intenet connection

Hello,

I am a user of a ReadyNas 104 with OS 6.2.3.

Here is my situation :

I have two internet networks with 2 distinct internet provider.

Network 1 : Very poor internet connection with dynamic IP(less than 1mbit) but reliable, in this network, I have most of my computers and devices.
Network 2 : Faster internet connection (6 Mbit) with static IP but very instable, could stop for hours then restart, I have my ReadyNas running on it with Qbittorrent for downloading.

I want to keep my readyNas with the fastest connection but how to access the Nas from Network 1 ? As there is two network card, I tested to connect Network 1 and Network 2 on the two distinct network cards but I was not able to reach the Nas from Network 1.

I tested to configure different static ip for each network with routeur and dns configured for each router but, there was a strange effect, I was able to see the two ip adress with raidar on network 1 (but card 1 was plugged on network 1 and card 2 on network 2).

Thanks for your input, I would be so happy that the Nas support this kind of scenario !!!

Have a nice day.