Hi @cristianbarni
You mentioned that it is not connecting to the internet,
mind sharing what is your ISP? I suppose it is ADSL ? what is the model of your ISP Modem?
Im thinking logically on your possible connection,
ISP Modem >>>
D-LINK WAN Port (PPPoE) for ISP >>>
D-Link Port 1-4 to your Intelbras WRN150 (LAN Port)
You mentioned windows not able to connect, are they in static IP or DHCP by D-Link router? how about DNS assignment?
try this
open command prompt (click start button and type cmd)
ping 8.8.8.8, is there any reply?
Note: Intelbras WRN150 should not have any DHCP activated, it should be managed by D-Link DIR615 Router.
Check for possible firmware updates for all devices too.