@deamon156 

Moving somewhat away from the topic, there is a suspicion that earlier routers used to have higher transmitter power, now it is usually limited to 20dbm.

Previously, there were few routers, and it was possible to make devices with a powerful transmitter. Over time, the number of network devices began to grow and conflicts began, so a power of 20dbm was adopted as a standard.

Now returning to your case, for starters, 2.4 GHz is now very noisy, usually from neighboring points in the immediate area.

look at what wifi channels the router is on in the 2.4 GHz range, limit the channel width to 20 MHz and set the least loaded channel

furthermore, the 2.4 network can also be affected by equipment such as a microwave oven; if it is turned on in the path of the WiFi signal, everything will be bad with the 2.4 wireless network.

2 walls are also a relatively difficult distance. If there are no doors on the signal path, but only two walls, then it is still worth trying to move the router closer to the center of the apartment.

In general, in a number of cases, due to strong conflicts and noise at the 2.4 frequency, it is necessary to abandon this frequency altogether.

the maximum that can be connected there in such cases is some smart devices, which, as a rule, do not have 5 GHz support in their network adapter.

my advice to you, buy a 5 GHz usb adapter, for example Archer T3U Nano, disable your native internal adapter in the device manager of your laptop and connect to a new router with a new 5 GHz adapter