@Abdulwahab there's an app on Play Store called "Netgear WiFi Analytics". Download it and see how many routers are connected to which channel. Then go in to the router's configuration page and select...

I changed the wireless channel to 2 and width on 40 mhz. I had 10 MB/s download and 9 MB/s upload. Thanks a lot for the solution. I have ~the same speed as on 5 ghz band.

I have like 40-60 mpbs on the 2.4 ghz band and 80-100 mbps on the 5 ghz band. Can someone help me solving this problem please? My wifi limit it's at 100 mbps.