Slow wifi speed Xiaomi 4C

Greetings! I have problem with my Xiaomi Router 4C. I have 30 mbps connection, but when performing test at speedtest.net, it shows me 15 mbps download speed and 30 mbps upload speed(at fact download speed should be around 30 mbps). I tested right now near router, it showed all 30 mbps. Well, when i started test near router, I did go to the same place where it was giving 15 mbps maximally. Magically, speed didnt drop and was same.. I was in same place and started test again.. 15 mbps.. I want to disable this buggy feature whatever it is lol.. Can it be "distance optimization"?

Did verify the problem, I want do disable thing that tries to do something with client when its signal becomes a bit weaker

which thing, what something ?

signal will get weaker by distance.

imagine i am staying 3 metres far from router speed is 30 mbps and when I am staying 3.5 metres far speed is 15 mbps

Thats the problem

If signal becomes a bit weaker speed becomes very low

speedtest.net isn't a reliable speed meter for your LAN/wifi, since internet speed will vary by the minute.

if you want to verify/max out the WLAN, use iperf3 on the router, and the client, when doing speed tests.

I was currently testing it with downloading files from websites
When I am near to router speed is fast(20-30 mbps)
But when I go a bit far it becomes 20kb-600kb/s
So I verified my problem
I was downloading from same website that is stable

no you haven't, since internet speed can vary you don't know if it's the internet that makes you speed drop, or you moving away from the router.

only way to check it, is not to DL anything from internet, when speed testing the (W)LAN.

Did thing which you told me
Ran from windows pc

Connecting to host 192.168.1.1, port 5201
[  4] local 192.168.1.178 port 55589 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-1.00   sec  5.25 MBytes  43.9 Mbits/sec
[  4]   1.00-2.01   sec  4.75 MBytes  39.7 Mbits/sec
[  4]   2.01-3.00   sec  3.12 MBytes  26.3 Mbits/sec
[  4]   3.00-4.01   sec  4.62 MBytes  38.4 Mbits/sec
[  4]   4.01-5.00   sec  4.62 MBytes  39.2 Mbits/sec
[  4]   5.00-6.01   sec  4.62 MBytes  38.7 Mbits/sec
[  4]   6.01-7.00   sec  4.88 MBytes  41.0 Mbits/sec
[  4]   7.00-8.00   sec  5.00 MBytes  42.0 Mbits/sec
[  4]   8.00-9.01   sec  4.75 MBytes  39.4 Mbits/sec
[  4]   9.01-10.01  sec  4.25 MBytes  35.9 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-10.01  sec  45.9 MBytes  38.5 Mbits/sec                  sender
[  4]   0.00-10.01  sec  45.9 MBytes  38.5 Mbits/sec                  receiver```

Output of server(router)

Accepted connection from 192.168.1.178, port 55588
[  5] local 192.168.1.1 port 5201 connected to 192.168.1.178 port 55589
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  5.01 MBytes  42.0 Mbits/sec
[  5]   1.00-2.00   sec  4.83 MBytes  40.4 Mbits/sec
[  5]   2.00-3.00   sec  3.19 MBytes  26.8 Mbits/sec
[  5]   3.00-4.00   sec  4.56 MBytes  38.3 Mbits/sec
[  5]   4.00-5.00   sec  4.57 MBytes  38.4 Mbits/sec
[  5]   5.00-6.00   sec  4.59 MBytes  38.4 Mbits/sec
[  5]   6.00-7.00   sec  4.87 MBytes  41.0 Mbits/sec
[  5]   7.00-8.00   sec  5.02 MBytes  42.0 Mbits/sec
[  5]   8.00-9.00   sec  4.79 MBytes  40.1 Mbits/sec
[  5]   9.00-10.00  sec  4.28 MBytes  36.0 Mbits/sec
[  5]  10.00-10.05  sec   168 KBytes  27.7 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.05  sec  45.9 MBytes  38.3 Mbits/sec                  receiver

wirelessly, I assume ?
stationary, or did you move around ?

yeah, that's wireless test. i didnt even move around, but i'm using wifi usb adapter so it will be easy to move a bit

well, you claim distance is a big issue, so moving around seems kind of important ... ?

Lol i just made my wifi usb adapter 0.5 meter nearer to wifi and look what test I got now

Connecting to host 192.168.1.1, port 5201
[  4] local 192.168.1.178 port 54214 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-1.00   sec  5.38 MBytes  44.9 Mbits/sec
[  4]   1.00-2.01   sec  5.75 MBytes  48.2 Mbits/sec
[  4]   2.01-3.01   sec  5.62 MBytes  47.2 Mbits/sec
[  4]   3.01-4.01   sec  3.50 MBytes  29.1 Mbits/sec
[  4]   4.01-5.01   sec  3.62 MBytes  30.7 Mbits/sec
[  4]   5.01-6.01   sec  5.75 MBytes  48.3 Mbits/sec
[  4]   6.01-7.00   sec  5.88 MBytes  49.4 Mbits/sec
[  4]   7.00-8.01   sec  5.88 MBytes  49.0 Mbits/sec
[  4]   8.01-9.01   sec  5.88 MBytes  49.4 Mbits/sec
[  4]   9.01-10.01  sec  5.88 MBytes  49.2 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-10.01  sec  53.1 MBytes  44.5 Mbits/sec                  sender
[  4]   0.00-10.01  sec  53.1 MBytes  44.5 Mbits/sec                  receiver

Lowest results were when wifi icon was like that
image
And higher when it was like that
image

Also I can't just forget about this problem because its very unstable that if I just move 0.5 meter far the speed becomes very slow. When my router had stock firmware didnt have problems like this wtf

I'd say speeds were consistent ... I assume they are tested from the place/distance where you say it dops ?

It's another place. I can't just move my pc that far. But in fact that is not normal that I just did move my wifi usb adapter a bit near to router and it speeded up.. O.o
Possibly.. router is trying to optimize speed or wtf?..

Well, if someone will have solution, tell me.. Revert to older versions is not a solution, only 21.0.2 is supported for my router. Thanks everyone who will try to help.

Sad, that nobody can help

I guess if I willn't be able to fix it, I will have to move to stock firmware, unfortunately..