Recently got Xperia X as replacement for under warranty z3c that had problem with screen separating from body.
As soon as I stared setting it up it was obvious there's something odd with wifi, apps took too long to update, buffering issues on youtube and so on.
So I made few measurements in relatively controlled environment with different equipment and was surprised to find how horrible wifi actually works.
I used wrt54 2.4ghz router with custom firmware for rssi, rate and link quality readout, iperf3 in/out, samsung mega and iphone 5 for comparison.
It works ok when signal is strong but degrades very rapidly as it starts to drop. When signal is still kinda strong "2 bars" transfer rates start spiking/dropping and are in general half of those on other phones. Both inbound and outbound rates are affected. Once signal gets weak other phones still pull 5-6mbit while X goes completely silent. Strange thing is you can't really see anything wrong with RSSI, it's couple of dB off but nothing dramatic, link quality is also inline with other phones however TX/RX rate drops to it's lowest value or is not shown at all. I did try reflashing firmware but it didn't change anything.
Has anyone else noticed something similar? The X I received as replacement is not new but refurbished, maybe this is isolated issue? Don't really know what to do, should have repaired z3c myself but it felt kinda stupid not using warranty for that.
