My down is 1Gbps and speed at the deco wired is around 350mbps.  Turns out in AP mode, at least on the 6 that I have, it seems to be limited at 350mbps plus minus a few.  Reset and reboot all devices, still same speed.  Tested the speed that is wired to the deco and got 950Mbps.  Connect cat 5e to the back of the deco and speed drops to 350. Contacted TP link and they tried very hard, even tech support got on the phone and loaded debug firmware on the decos to run tests.  I had 2 sessions with the tech and they could not figure out... and they gave up.  Basically said too bad we really tried and cannot find out the issue.  In AP mode I only get 350Mbps is not acceptable.  Now I am stuck with 6 deco S4R that only outputs max on the cat 5 at 350mbps.  Wireless is about the same.  Connected to the switch before the deco and get around 950Mbps.  In router mode however, it seem to be better.  It does not work in AP mode.