A laptop with a 802.11ac wifi module and a 2.4 GHz router + repeater, will the Internet work faster?

Question

WiFi

Guys, tell me please, there is an ASUS RT-N11P router, 802.11n standard, frequency 2.4 GHz, Max. wireless connection speed 300 Mbps. I used to have a laptop with win7 and the wifi worked fine, but I can see the frequency in the house is busy, I see the channels are clogged by inSSIder, and one day the speed became lower.
Now there is a laptop with win 10 and a Wi-Fi module of the 802.11ac standard for 5GHz.
The speed on speedtest.net directly with a cable to a laptop is 98mb / s, as stated by the provider 100mb / s of norms, but on wifi the speed drops to 20 - 30 mb / s, the router is nearby. 3 meters in direct line of sight.
So the question is, I want to get rid of the repeater for the time being to amplify the signal in order to increase the Wi-Fi speed, but the antenna icon on the laptop is full, and the channel does not seem to intersect mine with others, it dominates. Does a repeater make sense in my situation? Or save up for a new, more powerful 5GHz router?

Answer 1

And what is the channel width in 5Ghz in the router? And what is the channel number?

Answer 2

With an Internet speed of >50 Mb/s, in a high-rise building, you need to definitely go to the 5 GHz segment, because 2.4 is now over * ran so even MIMO 3x3 with manual settings will make the weather for a maximum of one room.
So here are the options either to change the router to a dual-band one or to pull in a repeater with AC and connect it with a cable to an existing router as a 5GHz access point, because. a weak transmitter in a free range will give better quality than a strong one in a busy one.