What you were seeing was the dreaded Buffer Bloat. It's really quite common nowadays. Memory is so unbelievably cheap, so device manufacturers all up and down t

What you were seeing was the dreaded Buffer Bloat. It's really quite common nowadays. Memory is so unbelievably cheap, so device manufacturers all up and down the ISO stack are putting too much memory in their transceiver buffers. Why is this bad? Because it screws with TCP window adjustments. Remember that your OS will send packets until it starts to see drops, then back off of the transmit rate. You can adjust the parameters (startup rate, backoff rate), but that's the basic principle. However, when there is an overly large buffer somewhere in the middle of the network, this delays drops. This has the effect of making it nearly impossible for your TCP stack to determine the true bandwidth. For some reason, most mobile device manufacturers are the worst offenders when it comes to bufferbloat. Anyways, this was a brief summary. For a much better explanation (including pretty graphs), see http://www.bufferbloat.net/ http://www.bufferbloat.net/