Why is the transmission speed low in a wifi network?

Question

Data transfer

I transfer files from a laptop to a smartphone, the maximum speed was 2.5 mb / s.
TL-WR743ND router and laptop and smart phone support n

Answer 1

First, you need to find the least noisy channel. Probably the neighbors have a lot of access points, and they interfere with your point (and yours interferes with them). You need to scan the air and find the least loaded channel.
On Mac OS, this can be done with the Wireless Diagnostics utility located in /System/Library/CoreServices/Applications.
In Windows, for these purposes, you can try the www.wifichannelscanner.com utility (I haven’t tried it myself, I don’t use Windows).
In Linux, as far as I remember, this is done by the iwconfig utility.
I want to note that, despite the fact that there are 11 or 13 channels in 802.11, there are only 3 non-overlapping channels.
Secondly, you need to see in what mode your access point works. For maximum speed, you need to set the Native 802.11n or 802.11n only mode (each vendor calls it whatever they want, but the meaning is something like this). But in this case, devices that do not support 802.11n (for example, 802.11g adapters) will not be able to connect.
In any case, even under ideal conditions, the transfer rate of useful data via WiFi will be no more than 60-70 Mbps (7-8 Mbps) with your access point (it has a channel speed of 150 Mbps).

Answer 2

two and a half megabytes per second is 20 megabits per second, which is not bad.