How can I make my D-Link router work with PhotoSync?
Many D-Link Wi-Fi routers have an advanced network setting for Multicast Streams in their configuration which is disabled by default. Multicast DNS (mDNS) is part of the Apple Bonjour Protocol that is used to detect the PhotoSync devices automatically (it is used in many other popular products as well, like Apple AirPlay for AppleTV, iTunes, etc.). You need to enable the "Multicast Streams" in the D-Link settings to make PhotoSync work despite all your firewall settings on the computer.
Use your favourite web browser to open your Wi-Fi router configuration, log on, go to "Advanced" > "Advanced Network", and check "Enable Multicast Streams" if it is not checked already. We got confirmations of users using a D-Link DIR-655 and a D-Link 615L that this setting is necessary to run PhotoSync.
This screenshot may vary by the D-Link router model.
It is also possible that your D-Link router supports a feature called "WLAN partition". If WLAN partition is enabled, clients in the same wireless network are not allowed to communicate with each other. Please make sure that WLAN partition is disabled, otherwise PhotoSync will not work.