Update: Finally got it to work, and I am posting how here to help other people with the same problem and X-Aviation in troubleshooting the problem.
This is how my computer is connected to the internet:
1.) The signal (DSL) enters the house and goes into a WLAN router.
2.) The line goes from the WLAN router into a second WLAN router (in my office), type Netgear WGT624.
3.) The line goes from the second router into my computer.
This configuration did not work with the download. However, when I plugged my computer directly into the first router (bypassing the Netgear), things worked flawlessly.
Off to some winter flying!
Jan