Thought I'd give Android 4.4.2 (KOT49H) a quick try earlier this week.
I was coming from a clean Cyanogenmod 10.2.1 install, before this I had flashed stock Android 4.3 (JWR66Y) for it's most up to date 4.3 bootloader/radio. Everything with CM 10.2.1 was working perfectly.
Whenever I flash a ROM I erase boot, cache, recovery, system, userdata first via fastboot.
Everything worked fine after flashing 4.2.2, enjoyed playing with it, wifi was absolutely fine at this point, but wanted to go back to CM 10.2.1 regardless.
Re-flashed Android 4.3 (JWR66Y) again so I got my bootloader and radio back (...I heard the KitKat versions don't play well with 4.3 roms)
Erased everything via fastboot again and reflashed back to a clean 10.2.1 install.
Now my wifi is CRAWLING 50kb a second when I try speed tests and play store downloads are unbearable!.
What I've tried...
CM 10.2.1, stock 4.2.2, stock 4.3
The only thing that 'fixes' wifi is going back to stock 4.4.2! What the hell happened? Any theories how something seems to have changed permanently since my KitKat flash?
You may say, why don't you just stay on 4.2.2, well, because I HATE not having the choice! I'm really keen to find out why I'm not seeing my normal wifi speeds on 4.3, what did it change?
I've searched, found ALOT of posts referring to wifi problems with KitKat, but not this one. Most of the fixes include changing my router settings. Obviously, my router was working brilliantly before so I don't think that is the issue.
(Sorry for the long question, any ideas would be appreciated!)