This seems to be an issue with the network at the Slingbox location, do you have the Slingbox hardwired to the router using a regular Ethernet cable or are you using a wireless/power bridge. Also confirm the upload speed at home to confirm that it meets the bandwidth requirements,
I had forgotten about this post because it is so old.
The issue seems to be about 70% resolved. About a month after the post a new firmware was mad available for the slingbox and since then my 3G and WiFi hotspot connections have improved dramatically. Where I have run into problems is on the New Jersey TPK south of exit 6 which I think is just poor 3G coverage. I have also run into trouble on the Long Island Expressway and 15 and 405 between San Diego and Orange county but I think this may be because of traffic on the network. When I am in the mid west its a **** shoot because I'm usually out driving though corn fields trying to get to where I'm going.
The Sling is connected with a hardwire directly to my router and out through the cable modem. I have on average 7 meg up and 25 meg down, but it seems as if the update to the sling box in october time fram corrected things.
Long Island, New York