Which DLNA Controller app are you using? I have an Android 2.3-based tablet and the BubbleUPnP app, which I really like the UI. It all worked great with my old Sony SMP-N200 (DLNA renderer) but now I have a new Denon AVR-3312CI same as you. The app 'sees' the Denon on the network but all attempts to push music to it are ignored.
In your Denon's config, did you enable the Network Standby mode? This is what allows it to show-up on the network when it is 'off' and to auto-wake when you try to send it a song.
I just called Denon tech support, 800-497-8921, and they were very nice but not very helpful. They took my name and number and promised to call me back after testing BubbleUPnP on the 3312CI. They also said that they had previously tested Twonky and claimed it was compatible. I didn't like the UI on Twonky so I hadn't tried it on the new receiver, but now I guess I will.
I have set the configuration to N/W standby mode. Occasionally denon avr 3312 shows up in the app [bubbleUPnP/Music player] but i cannot get it to connect.
Will call denon customer care... keep me posted if you get it working.
Twonky is better at troubleshooting, e.g. in the menu there's a Active Players diagnostic. From that display I could see what previous action the unit was still trying/failing to do.
I did a lot of testing last night and what I found is that the DLNA renderer appears to lock-up (at least partly) with very little provocation. When it happens there's no indication on the front panel or even in the TV output. Instead, it just ignores most new requests. You're supposed to be able to stop it by pressing the Zone power on/off button along the bottom row of the remote, but I don't think that actually works. Instead, the only thing I've found effective is to yank the power cord for the whole receiver! After that, it works 'normally', even with BubbleUPnP. Until it crashes again, e.g. when you try to switch songs
Denon has been very responsive, so far! I already got a call back, asking for more details. Hopefully my complaint is about to be escalated to the second-tier support?
P.S. Twonky also shows both the DLNA and the AirPlay modules as available players. Be sure to use the one with the receiver-icon, not the one with the white add-on module icon.
I received a call-back from Denon but only to clarify which file-types I was playing (typical cbr and vbr MP3s!).
I also found that if I pull the power-cord, then restart the receiver, everything worked great. I could stop/start the playback (though the pause command didn't work), switch between BubbleUPnP and Twonky, without issue. But then I pushed the main power/standby button and nothing worked after that. So maybe there's a bug wherein the DLNA module crashes/locks-up when you put the receiver in standby?
FYI - I returned my Denon AVR-3312CI. I had disabled the Network Standby and that had made it at least usable, but it continued to balk on various MP3's. Then I got a call back from Denon tech-support (who were very nice and tried to be helpful) saying that their official response was, "We don't support variable-bitrate MP3's". What?! Anyway, I'm going back to my Sony SMP-N200 external media-player which works perfectly and without all this drama.