Ok, so I finally got a moment with the 655 and Guest Zone, I did a reset on the router to see if maybe this might clear this up. It didn't. So I downgraded to v2.07 and this version doesn't exhibit bad behavior with GZ.
So I'll recommend anyone using or attempting to use Guest Zone and seeing connection problems and if your router is loaded with v2.10, please downgrade to v2.07 or v2.03.
Please factory reset, downgrade using the .bin file for the version of FW your trying to downgrade, after the file is sent and the router reboots, do one more factory reset, then configure the router. Guest Zone works after that.
I have forwarded this on to DLink.
If your concerned about this version, please phone contact DLink support and advise them of this issue that has been verified here. The more visibility we present them the sooner they will review it and fix it.
Thank you.