I have already posted this to a couple of router/networking groups but given the enormous breadth of knowledge and experience here .....
I had a network running off a non-wireless DG834 and a cheap wireless access point.
Got a DGND3700 to replace them. Connected up, set up and all worked fine including wireless. Left all connected. Returned a couple of hours later, no wireless signal.
Have changed settings, rebooted, done factory resets etc but wireless seems to work or not at random.
Unit is in a well ventilated area and is only warm.
Any ideas?