WiFi 5 Ghz only: Signal strength excelent, but link speed varies between 6mbps and ~400 mbs

[Maili]

Hi @all,

I own a Xperia Z3 tablet compact (SGP621).

Problem is as described in subject. I have no problems within the 2.4 Ghz net, there it shows almost constantly 144 Mbps.

When connecting to the 5Ghz net, "WiFi Network Analyzer" gives me link speed of more than 400 Mbps, within about 2 minutes it reduces to 6-13 Mbps. Sometimes link speed increases to more than 200 Mbps for a short time again, then it falls back to mostely less than 30-40 Mbps

I tested while sitting beside the router, which is an Asus RT-AC68U

I checked the channels and moved it a bit, although we live in a rural area and there was no overlaping, but that didn't help either.

So I did sent my phablet to the official repair center of Sony at Germany, but they "couldn't reconstruct" the problem and didn't do anything but sending back unchanged.

Newest firmware is in use on both devices (phablet and router), hard reset is already done on the tablet, but the varations remain. 

Does anyone have an idea how those variations can happen?

Thanks in advance

Frank

[Rickard]

What happens if you start downloading something in your tablet (for example a large app from Google Play)? Does the link speed increase when you do this?

[Maili]

Hi, thanks for your response!

I will test it today, but as far as I remeber, sometimes it increases, sometimes it stays on 6-12 mbps, and sometimes it says "no connection to internet available, try again" (or something like that). Then after 1-2 trials, it starts dowloading, mostly with increasing speed. 

I use the app "WiFi Network Analyzer" for determinating the link speed, would it make sense to make some screenshots about the speed?

I 'll let you know today after testing

[Rickard]

Screenshots will probably not show what's causing it.

But also try updating the firmware in your router if you haven't tested this. I checked a forum about this router and there seems there was a fix for 5GHz in an update for it.

[Maili]

Thanks for the hint, this is usually the first step I check. Indeed there is a new firmware for the router which I install right now (I had the version befor the newest one). Nevertheless before updating I made a couple of tests, all of them were imho excellent. Link speed increased from lowest 6mbps, second and third test from 40 and 117mbps up to the maximum (theoretical) value of 866 Mbps, the physical up-/download was around 250mbit/s.

So today I couldn't reconstruct my problems. I will hang in, maybe there is an influence from "outside" I didn't consider.

Only thing I changed today is that I dropped the 2,4 connection from the Sony, so it got unknown to the device.

Thank you very much for your advice!

[Rickard]

Glad to hear that you're getting a good connection now

In case it should happen again, perhaps also test turning off WiFi in other devices connected to your router and also try switching to another channel if you haven't tested that.