The Wi-Fi reception rate on ASUS RT-AC55U fell

I have a router ASUS RT-AC55U Internet 100 mbps. Recently I noticed that the Wi-Fi speed has dropped, and only on reception, namely, if earlier the speed in the 5 GHz range in speedtest on iPhone was 70/70 mbps, now it’s 35/70, a little less, but also dropped the reception speed in the range of 2.4 GHz. At first I thought that it might be because of the new firmware, and flashed to the previous version, but the speed could not return. Tried to do a factory reset also did not help. What can it be and where to dig?

Answer

Internet speed, especially over Wi-Fi network, this thing is very unstable and unpredictable.

I think the first thing you need to do is to make sure that the speed is not limited by your ISP. You need to connect the Internet directly to your computer, or at least via cable from the router. And check the speed.

Also, the speed may drop because of some interference. Although at a frequency of 5 GHz it is unlikely. You can experiment with channel settings and channel width for 5 GHz frequencies.

I would still install the new firmware back.

I don’t have any other options as to why the speed dropped.