Why fell the speed of data transmission over wi-fi on the laptop?

Hello, the problem is that after reinstalling the operating system, fell the speed of data transmission over Wi-Fi. The contract provider provides me with Internet speeds up to 100 Mbps, it is clear that the main thing there before, but nevertheless, on the downloading torrent is holding steady 7-8 MB/s, and sometimes all 10. Now the situation is that on the laptop the download speed maximum 5Mb/s and so 4 - 4.5. Although desktop PCs are fine. The laptop is located at a distance of 30 cm from the router, up to several meters. And there was a need to temporarily replace the wifi module and both of them show the same result at 4-4.5 MB/sec. Router if TP-Link WR841ND, which accommodates up to 300 Mbit/s Wi-fi Modules Qualcomm Atheros QCA9565 and AR5B195. Also apply the results check the speed of your connection. What could be the problem?
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July 4th 19 at 23:58
2 answers
July 5th 19 at 00:00
the reasons can be many.
stationary computer via wire or wifi?
to check the load on the channel Wi-Fi (wifi analyzer and similar apps) and, if necessary, to move to less congested.

if possible, test another device (phone, tablet, laptop)
one-on-one with a router, everything else off. if the customer is unknown. the ban means router.
1.
loaded with lausd, to test the speed.
drivers. put new/old
BIOS throw/update
to check the encryption. only wpa2+

to update the firmware of the router, to reconfigure.
to see the router from all possible sides, antennas, capacitors, etc
July 5th 19 at 00:02
in the settings of the wifi driver is not permitted to use 40 MHz channels, and Wi-Fi

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