First gen surface pro wifi issue topic

I have the usual wifi issue where in surface pro only gets 2-3 mbps speed while all my other 6 devices get 16 mpbs, yes my router only supports 2.4ghz mode.. but the unusual thing is, i have this other router which i borrowed that supports both 2.4ghz and 5ghz modes.. in that router if i connect even to the 2.4ghz access point i get the intended speeds ? how come .. i thought surface pro has some issues with the 2.4ghz modes.. this is weird.. any way to fix this without buying a new router? i have tried the registry edit method(AutoUse40Mhz, band), updates , all sorts of thing.. nothing works with my router .. i have a NetGear WNR3500L V2 btw.

Also it gets too hot 65c with just couple of tabs open in chrome ..

Any help is appreciated.