I have the same problems these days as everybody elese has them. I live in northern Kunming and am connected via 4mbit ADSL (4096ks down and 512ks up) and from day to day the speed of my connection changes. From almos no connection at all, to damn sluggish, to pretty fast.
I tried to delete all "domestic" failure sources; put other routers, put other modems (yeah, i'm a geek but not a pro) but nothing improved helped.
Like 6 month ago one could say: I have fast internet to 10am (that's when the offices start "working") then it will slow down and get fast again round 10 in the evening.
So the problem lies directly at the border of China-mainland and is called "Project Golden Shield" (scary hugh?). It's also known of course as the great firewall. So when you understand how it works it's pretty easy to understand why speeds can differ that much here in Kunming.
If you type in an URL and hit enter, a request is send to the dns server (normally) and after that you computer actuall starts downloading the page you requested.
Here in China these request is captured by the golden shield, which will first of all copy it. Then it's transferred to a pretty strong server, while setting you original request on hold. The server will start downloading the page you requested and scan it for unapropiate content. If it's clean your original request get's it's permission to travel through the shield. If not, you request is simply denied and you get the nice "this website is not avaiable"or "the request timed out".
The big problem for this is chinas limited connectivity to the "rest of the world" there are only 3 or 4 outgoing connections, this is what creates a pretty nice bottleneck.
Actually the response time of you connection sometimes goes up by almost 1000% (means the ping time rises from around 80 to 800ms). But also the data transfer rate is bottlenecked.
What can you do about it? For me, a vpn (virtual private network) is the tool of choice. VPN creates a so called tunnel between two computers anywhere on the earth. It's like pulling a really long LAN cable round the globe, without any steps in between (ahh, except of golden shield).
A VPN connection is secured, means that even golden shield can not examine it's contents. But: It slows down VPN connections in the same way it slows down any other connection, by simple giving it some extra rounds in a big server.
You may ask why, and my answer is: I do not know. Maybe they want to artifically slow everthing down to prevent every chinese to use vpn's.
And before you ask..., VPN is a pretty safe investment for the future because golden shield can not stop all VPN-connections because literally every western company in china is hooked up via VPN to it's home computer anywhere in the world. Second of all, all bank transfers are made via VPN and it's very hard to cancel them all.
So how do can one obtain a vpn connection. There are millions of services out there. First of all one should be aware, that in a VPN, your computer get's the IP adress of the computer at the other end of the connection. So if you VPN is based in america, you will get an american IP (enabling all the nice little content on hulu, youtube, etc...).
Just google for VPN.
My tip: Try "Anchor soft"s "Hotspot shield". It's designed to secure your connection from Wirelss hotspots but works via a VPN. And it's free (of course you will be served a little bit of advertisement).
So if you realized that you're in China and can't really influence the speed of your connection to "the rest of the world", but realized you can work on the reliability and wan't to tryout a VPN service, this could be a start.
So, as I said I'm not a professional. If I'm wrong please correct me, I gathered this information all around the net.
And please, do not use VPN's to reach blocked sites in china, since this is illegal. Thanks.