So wireless coverage is largely the same on most decent routers. The main issue is the restrictions on output set by the EU, so wireless can only be so powerful. There are other factors but I have personally found all routers to perform similarly, with the odd exception.
The best way to boost the signal is to keep the existing router, then run ethernet to where the coverage is poor, here connect up a second router. Name both routers the same and set them with the same WiFI password. Set one router to channel 1, the other to channel 6. This way they wont interfere.
Turn off DHCP on the 2nd router which basically means the main router does everything important.
Now as you walk around the house, devices will automatically switch between the main router and the second routers signal.
It will only be seen as 1 network, not 2. So in the iPhone for example, you will just see the network once.
This is how large businesses, schools etc do things. You only see 1 network name but there's often 10+ routers broadcasting that name. Your device just connects to the best signal.
Hope I've helped.
Other options are available but they don't always work too well. This methods a sure thing, guaranteed to sort things out (using ethernet and two routers).
I personally use homeplugs, they are great in my home but some people find them dreadful (it's dependent on your home wiring).
With WiFi Homeplugs, connect one to your main router, plug another in where the WiFi signal is poor. Again name both the homeplug and main router the same. You will seamlessly migrate between both. For me I get over 70Mbps on Homeplugs but others find they either do not work, drop out or are very slow. It's all down to your home wiring. Maybe worth trying though? Mine work flawlessly.
Edited by ukhardy07 (Fri 27-Mar-15 20:59:49)