@N3kko 

Hey

Sadly what you are trying to do is not viable using a switch.   This switch is unmanaged and therefore just allows everything on every port to communicate with each other.  What you are trying to do is ISP Load Balance and VLAN traffic

To do this you would require a Load Balancing Router, something like the ER605, and a managed switch capable of separate VLANs (SG2008 for example)

Set the 2x WAN connections on different VLANs for the ER605 and trunk this via the switch to the devices you require. 

This is not something that could be done via the home grade hardware, you would best looking at the TP Link Omada range.