sandropadin :
To me it seems as if all the cables are configured the same, but I don't see why. 3 should lead to ethernet jacks and one to a telephone jack. I also don't understand why the brown/white and green/white cables and not connected.
The jacks are configured for telephone service only, not Ethernet.
The cable connected to the left should be your incoming line. The other cables go to each of the 4 jacks.
Blue and blue white wires are for the primary telephone line, while orange/orange-white are for a secondary line.
As configured, you cannot use this for Ethernet. If you wanted to configure the inside lines for Ethernet, you would need to disconnect these wires, terminate the ends with RJ-45 plugs and place a network switch here.
Alternatively, you could enable one jack for your router and one for a PC by splicing two of the desired cables directly together, color for color.