The security router is found at ground level of the marked aparment. There are no switches to be unlocked and the router can be hacked easily as well.
The security router is at ground level but you need to find the switch consoles before you can unlock it. The first switch console is located at the rooftop of the building southwest of the marker. You need to view it using a camera. There should be one camera from the building across it that you can control and use to unlock the switch console.
The second switch console is located at ground level, beside some dumpsters. After unlocking the second one, you have to hack the camera from the other building so you can find the last switch console on the rooftop of the building where the activated line leads to.
The first switch console for the security router is found to the west, in the corner of a house. Follow the activated line and it will lead you to the second console. Finally you can intrude the security router with ease.
The first switch console for this security router is found to the east, in the corner of the buildings beside an electric post. Follow the activated line and it lead you to the second console on the balcony of a building. Unlock it to finally be able to intrude the building marked in the map.
There are two switch consoles you need to hack. The first one can be unlocked by using the corner camera installed on the building to the west of the P.I. marker. Follow the data connection to the second switch console on top of a small shed and unlock it.