2.4 G network bumped from 144 Mbps to 300 Mbps

This is for 2.4G Network-mode only.
Not all wireless clients can support this, but here it is...

Open your router configuration panel (if you do not know how to do that, google search it for directions)
The browser address and username and password for that configuration panel login is usually shown on the router itself.

Once logged on, open the wifi widget (tab) and then open advanced settings and change the Width from 20 Mhz to 40 Mhz
(in some cases it will show as 20/40, which is the one to change it to)
With that done, you are now bonding 2 x 20MHz channels into 1 x 40MHz channel for double the bandwidth.

Connect your android device and you should see the Mbps go from 144 to 300 after this is set (or there abouts, depending).

I have done this and it does work.
Before you do any of this, first check at what your (2.4 G wifi) Mbps is shown on your android device, so you can see the change after the procedure is competed.

Another useful tip from Andy
thnx Andy :)