I have the Denon Binding working well on OH2b3 on Windows 8. Both http and telnet protocols are working.
I have a second older Denon AVR that does not have ethernet, but does have serial, connected with an IP2Serial device (Digi Portserver).
I have read elsewhere that the Denon telnet commands are identical to the serial commands. And I have successfully controlled this Denon with iRule and SimpleControl (formerly Roomie) this way.
I believe that the problem is that the setting for telnet control is hardcoded to port 23, (and http is port 80) and there is no way to change the port in the denon.cfg.
I noticed that the Pioneer and Onkyo AVR bindings do allow you to set the port.
If there was a way for me to change the default port of the telnet protocol, I could probably control via the serial port using my portserver (or a global cache IP2SL).