Denon E400 firmware update loop

My Denon E400 is a nice AVR, but for some reason fails to do firmware updates if plugged in to my Ubiquiti Toughswitch. If I attempt an update it fails to connect to the server for some strange reason and gets stuck in an update loop with an error on the display that looks like

ConnectionFailed10e

The fix is to do a Network Card reset, which on this model happens to also be a microprocessor reset. Unfortunately you will be stuck with factory defaults, and this model doesn't seem to let you do a backup/restore of settings.

sigh

Anyway, the trick is to power off the device and hold down

[SOURCE SELECT], [->] and [ZONE2 ON/OFF]

while powering on until the display starts blinking for a few seconds. For the record, the regular microprocessor reset is holding down both of the SOURCE SELECT buttons while powering on and wait for the display to blink a few times.

Update, 2/19/15:

My friend has an AVR X4000 and he needed to do the same after trying to update while plugged into a Ubiquiti. He called Denon and his reset sequence was the following:

• Hold down the up and down buttons and power button simultaneously
• Let the screen flash 5 times
• Release
• Navigate to the Setup Menu with your remote and then exit