I've seen some sentences, and some of them use 上网
:
通过上网聊天,我认识了很多新朋友
Through online chat, I meet many new friends
whereas for another case, it uses 网上
:
网上购物是最流行的生活方式
Online shopping is the most popular lifestyle.
In both sentences, they mean as "online". But I'm a bit confused on the word order, when should we use 上网
and when should we use 网上
?