Sorry you had so much trouble with the 3312. I had a heck of a time with steaming anything to a 2112 and Ci tech support (highly recommended over Consumer tech support) wasn't much help. That guy on that day told me to go static IP FWIW. Thank goodness for people like Matt. I hate they lost Jeff, he was another bright light at the end of the troubleshooting tunnel.
Network standby is the first thing I fix out of the box (followed by update notifications off). Now, do you turn network standby on or off? Depends on the AVR since they switched the d**n terminology on us last year. Deep breath.
Problems like you've had are the reason we limit what the customer can do. The Denon app is great for installers and DIYers but it wouldn't be any good for any of our customers. A programmed iPhone control system is one thing but the free app opens a can of worms for us. If you give them the ability to screw up something, they will.
Our "LAN tester" collects dust since we got a BERT bandwidth tester. They are painfully expensive but if we had had it before one particular install it would have paid for itself 2 or 3 times over in eaten service calls due to ONE cat5 (18" long) that had a correct pinout but wouldn't pass data correctly. If it passes a BERT test, it WILL work, period. You can't say the same for a pinout checker.
Sorry for being so longwinded, what I meant to say was "awesome, glad it all worked out in the end".