I was able to bypass my ISP gateway and use the Deco as the only device.  I have found that after a while, my Decos reset and I get stuck with a half duplex connection to the ISP connection.  To prove this theory i added a managed switch that just has the ISP connection and the main Deco.  I show full duplex and have 800+ speeds, after the reset the main Deco goes half deplux and I am under 100 MB.  Has anyone had this issue?  I am about to return this unit.