Yes, there are. PhotoSync uses the Apple Bonjour Protocol (like AppleTV, AirPrint, or AirPlay) and there are some brands or models of Wi-Fi routers which have known problems with the Multicast DNS implementation (mDNS) that is used by Bonjour. The effect is that PhotoSync cannot find other PhotoSync devices in the same Wi-Fi network. The only alternative is to switch to Bluetooth transport between iOS devices and to active the websharing and use a webbrowser between iOS devices and Mac/Windows PC's.

There are no official lists from Apple but there are a lot of Apple Support discussion threads that confirm the following Wi-Fi routers as non functional or problematic:

• D-Link DSL-2640U
• D-Link 2740R
• D-Link DSL-G604T
• Belkin
• LinkSys WAG160N
• SonicWall TZ-190 and TZ-150
• Qwest ActionTec (complete series) [see]
• Hwawei/Huawei HG256s, HUAWEI Echolife HG532