A couple of users have reported that they needed to reboot the HE hub to get the telnet connection to the receiver to work.
Also, open the log in a separate browser tab, enable debug logging on the parent (DenAVR) and the child (Onkyo AVR Main) devices, then click the Initialize button on each device. Then check the log to see if there's anything telling in the debug output.
EDIT: looking at the screenshots it appears you're using the Onkyo Multi-Zone driver. You may want to look at this thread
