@modytroy 

Nothing you can do, the 300 speed is what the unit is capable of, the 144 is what your actually transmitting/receiving at, see it like a fast car sold to you in a place where the speed limit is locked at 100 kph, when they promote these things it should say UP to 300 but no more rather than just 300, the lower speed could be a number of factors like walls, different levels in the house to where router is to where the wifi device is, upstairs/downstairs so to speak, hth.

@Hannibal_Lack 

Thank you for your reply

I have tried to connect with different devices and the speed doesn't exceed the 144 although I am right beside the router

I have other repeater N300 and when I connect with the same laptop i recieve the 300 mbps, do u think the problem is with the router itsself

Thanks for your cooperation

@modytroy 

Strange one, you say the router can't do 300 but the repeater logged into the same router can?

I'm afraid with that I am out of idea's for it, all I do know is that the claimed speeds of all routers are just a hypothetical maximum rather than what you can actually achieve with them, could be a software glitch that is telling you one device can supply 300 where it reports the other can't, bit like car MPG figures claimed in a lab rather than out in the real world stuck in traffic, I would test it myself by downloading a 100mb file from say Nvidia both with and without the repeater and time how long each one takes to complete, if they both arrive in the same time frame it would indicate that the benchmark software for either or both units are flawed and giving the wrong readings,

Anyway I hope you find out why and if in any doubt return it for another unit if the warranty is still valid.