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Mine never even stays at 4G, it keeps going to Edge and rarely ever works. :/
I always limit mine to 3.5G since it's more than enough and a lot more battery friendly.
I use 2G, it's exactly the same speed as 3G or even 4G.
For me 2G seems to be much slower than 3.
Poor you :( My wifi doesn't reach the pillow area of my bed so I have to use 4G there whenever I want to watch a YouTube video before sleeping. (Wifi works perfectly down at the feet area). But damn, all the data is used so damn quickly with 4G.