Brand New HTC Desire C Wi-Fi won't work
Solved myself:

I tried after reading a lot of stuff to tweak my router and do a firmware update and I totally messed it up and almost destroyed it. It actually won't work at all and won't be found by wireless or anything, but it was already 5 years old, so I did not mind too much, I went and bought a new one (LogiLink - heard this brand for the first time, but works like a charm). I installed my new router (even though it asked for some things I heard for the first time in my entire life) and it runs on 802.11n perfectly fine for all my 3 computers and all my 3 phones. So turns out my old router was too old apparently. 

In conclusion, for anyone reading the question, I believe a firmware update on an old router if done properly (in which I failed horribly) can fix this problem, also as @MatthewRead pointed out in the comments mixed b and g was fairly worse than g only, so you can try this. In any case,