My receivers are hardwired directly into a Verizon FIOS modem and have no problems with network connectivity tests / using Sirius, Pandora etc. When I turn on the unit, I get a notification that I need to update the firmware, so I hit OK, and then the unit resets and I get a message "Update Retry Please Wait." That sets the unit into a loop, that it never gets out of. I took my X-3000 back to Best Buy and returned it for an X-4000. They'd never heard of the issue either... Decided to try the X-4000 instead... Same thing on the firmware update: "Update Retry Please Wait." If you wait long enough, you get a "Connection Fail 21" error.
I called Denon support and was given these instructions to get the unit out of the firmware loop (it worked):
Here is the instructions for a NIC card reset on a X4000 to get it out of its firmware loop.
Step 1: Turn off unit hitting the "on/standby"
Step 2: Hold down the "Up and Down arrow" on the front of the Denon. This can be located in the drop down cover.
Step 3: While holding those two buttons turn the unit back on. The front screen should start flashing. Let it flash 5 times and then let go of the "Up and Down" arrows.
Completing these steps will reset your unit and kick it out of the firmware Loop.
While that method successfully restores my receiver to factory settings, I still am unable to update the firmware. I'm within my 30 days still, and am ready to return this product if I can't reliably update the firmware.
BTW, this was the last communication I received from Denon regarding the firmware, as they've gone silent in response to my last emails.... Total BS answer as I have been trying for 3 weeks now... It's irritating as hell, because it requires me to redo all the settings every time I fail the update.
If anyone has a solution, please let me know. This is 2013--your network device needs to be able to update it's software without problems (see any TV, DVD player, AppleTV etc etc).