2.4G wifi routers switched to dual band 802.11n in the mid 00s. Unfortunately this means they use channel 6, plus another channel (usually 3 or 9). Most people rarely switch this off in their routers and a lot of ISP routers leave it configured by default, even if they also support 5G.

What this means is that channel 6 gets really crowded, and adapters which support single band only usually end up with really crappy performance because they can't connect to that second band channel.

So trying to turn off 802.11n and making sure A and G compatibility is on, and setting single band, and using a low channel like 1 may indeed work for solving these kind of problems.

I personally used channel 13 when I lived in a flat with around 20 other 2.4G networks crowding the airwaves, and that worked really well - with the problem that many drivers (especially those meant for the US market) don't actually support channel 13.