Possibly a slower connection than the test shows? Could be going through a cached proxy server locally.
I've run those speed tests and have seen 70 mbits both ways! :Q Do I see it here? Of course not. I'm told the bandwidth is about 600kbits both ways from the leosat receiver but those flash based tests show much much higher.
It's probably packeteered. At least mine doesn't time out like that. I did install a firefox add on called fasterfox and cranked it up and nothing loaded right. The IT folks said the system shut down the http traffic to my system because it was opening too many connections! So if you have something like that on this can happen too.