DLink DIR-300 Why does Wi-Fi speed drop a lot?

Question

Computer networks

Hello. For some reason, DIR 300 began to significantly cut the speed of Wi-Fi when switching to a new Internet operator. Through the LAN of the router it gives out 60 Mbps, through Wi-Fi no more than 10.
Below are the Wi-Fi settings that are in the interface:

Answer 1

Set the channel manually . If there is something to see what is happening on the air, then set the freest one, if not, then at random, well, I don’t know, channel 11, for example, if it gets better, leave it, if it doesn’t, change it to another, etc.
Change the mode from G to N
Beacon period ... Well, I set myself 50, I didn’t notice the difference, the laptop finds the router just like before and connects for the same time. So, you can also set 50 ether even for a penny, free up if problems start, you can always return it to its original position.
Channel width 20/40MHz-, in principle, you can leave it like that, but the wider the channel, the greater the speed. So you can try setting it to 40MHz, but keep in mind that the wider the channel, the more interference, that is, the effect can be quite the opposite. If everything is completely bad on the air, set it to 20MHz, at least it will work more stable.
What firmware do you have? Maybe just BETA? Maybe it's time for an update?
Is the power supply supplying the correct voltage?

Answer 2

Change wifi mode to N
en.wikipedia.org/wiki/IEEE_802.11#802.11g