5Ghz issue here,too. No internet traffic, sometimes slow. Have to switch between 2,4 and 5 Ght to solve it for a unreliable time. No Problem with 2,4Gz. Router is Fritzbox7490, VDSL 100 Mbit downstream, 44 upstream. OTA on 5.4.3 with full factory reset. Very disappointed on not reliable 5GHz...