You said you tested it at home; I'm assuming via wifi on the laptop or via an ethernet connected pc thats on the same network (router) as the slingbox. this is why your getting speeds of 4000kbps.
Your remote viewing experiance is directly dictated by your ISP's upload speed at the slingbox connection. I'm assuming it's rated for 768kbps by the speed you posted your gettign in hong kong.....
To get a better remote picture, you need to increase to a higher package that offers more bandwidth for upload at the slingbox's hosted address. The higher the upload speed, the better the remote viewing experiance and picture quality will be. For example here in the states, comcast (my isp) has the following packages available:
1.5 mbps down, 384kbps up
15 mbpd down, 3 mbps up
20 mbps down, 4 mbps up
50 mbps down, 10 mbps up
There's NO way your ISP is rated 10Gb/s; I think you actually meant to say 10Mb/s.
At any rate, what is your "upload" rating at the hosting location in Washington (the upload, not the download)? On a computer from within the slingbox's network, go to www.speedtest.net and choose the closet city letting it run the bandwidth test to find your true download and upload speeds. Please post the results here so me or someone else can further assist you in trouble shooting the sistuation.
Remember, you can only get a quality equal to the slowest connection. What I mean by that is you can not exceed the Kb or Mb rating of either the upload hosting locations speed rating or the remote locations download rating (whichever is lowest).
I get the same problem on some networks. I have an upload speed at home of 4mbs from where i upload the picture and i get a full speed when downloading at one place and a max of 1mbs when downloading at another place.
Clearly this is an issue with specific routers that is like they have a cap on download speed since they have a download speed of 3mbs and i download with a standard of 1mb.
Do you know how i can resolve such an issue on a ZTE router?
Don't forget that an internet stream does not come straight from your home to your location. I did a ping on my communication to a remote location from my home and it passed through SEVENTEEN different servers. It only needs one of those to be having a bad day or a bit overloaded and your own upload and download streams become irrelevant.
This does not seem to be the problem. In the same house that there is the ZTE router that i use to download the stream i removed it and put the old thomson router that a friend has in his house. Just to figure out what the problem is. Both routers are used by the same provider.
The old router downloads with 4mbs and the ZTE with 1mbs. As simple as that. Same house same provider same download speed same laptop.