The best way to solder/desolder such chips - is to use hot air gun or hot air station. It may be professional (ERSA, PACE), hobbiest (AOYUE-6031 Sirocco, AOYUE-908, etc.) or even good workers hot air gun (Makita HG650 for example) with small nozzle.
Some people upgrade router with an old soldering torch only, but this is not so accurate and require much time.
I strongly recommend you to train on something else before hacking router, for example - old PC expansion cards, motheboards, etc.
Anyway, you have to use good paste Flux (for example, http://www.efd-inc.com/Solder/Flux/ - good, but expensive) and always check quality of soldered pins. Most comfortable is to use stereo microscope, but magnifying glass is acceptable too.
