Occasionally I need to connect into work via VPN from my home. When I try to pull down a file (tens of MB) often the download will fail partway through when I use WiFi, but it rocks in with no problems when using a wired LAN connection into the WiFi router.
We have a pretty quiet WiFi spectrum around here; I cannot see any other APs using our channel.
There doesn't appear to be the same problem of interrupted downloads outside of the VPN.
Where do you think I should start in diagnosing what is going wrong?