After upgrading my internet plan speed, I reset it and disconnected everything to check the speed on a single device to remove any interference. I guess problem is 2.4Ghz limits which is 40mbps.

Basically, the problem is tied to the router, right? inshort I have to buy a router which has 5Ghz with greater range.

I have D-Link DIR-816, which says 300 mbps.

if I turn off my 5Ghz band I’ll get max speed in 2.4 Ghz right?

so 40 mbps is the maximum for any 2.4 GHz router in the current market?