I must be doing something wrong as I can not never force a CE download. I follow the instructions but I can never get it to go...
The two biggest factors that got in my way when I first started doing CE downloads were the timing of when to start typing in the 02468, and then the speed at which you type in 02468. I think this is mentioned in the "How To" portion of the CE forum, but think of it as 0...1,000...2...1,000...4...1,000...6...1,000...8. I also realized that for whatever reason, my universal remote doesn't work for me when punching the code. Be sure to try doing it with the D* remote.
Now back on topic: If you are using DHCP with your router, try rebooting everything in the IP pool to refresh the tables in the router. Maybe simply rebooting the router and the HR20 will do the trick.