My setup here: XA2, Verla and Fritz!Box 6591 with two meshed 2400 repeaters. 2.4 and 5 GHz Network, WPA2 (CCMP), canal auto selection, about 70 2.4 GHz Networks and about 14 in 5 GHz range nearby. Normally 3-6 active devices.
This worked similarly well with my Xperia X when I had a 6490 and only one repeater.