There are multiple ways to share the same address book, they are described in this section. So long as you are already using the Server, then the best way to sync the book will be through the server. I highly recommend then that you start using the 6.5 beta version (downloadable here), because in this beta the entire sync mechanism and security model has been changed and vastly improved as compared with the current stable version and previous versions.
Don't hesitate to ask me if you have other questions.
Unfortunately, it is how it works on Windows 7. The new monitor driver that we implemented in the recent beta version and that fixes many issues with "blank remote screen" feature only works starting Windows 8/10.
So I shut down Webroot, started the service and it's been connected now for more than an hour! Although I do have to report a few minutes ago the icon for the host is no longer in my taskbar, though the service is still running and I can connect/logon. I do have rutserv.exe, rfusclient.exe, ripcserver.dll, and rwln.dll all on the Allow list in Webroot. I restarted Webroot and within a couple minutes the service crashed.
So we found the reason. I'm afraid the only remedy here would be to contact Webroot and report this problem. We do our best to keep the number of false positives low, but as you can see there is always something that slips through the cracks. A/V companies usually pay little attention to their fellow software developer requests, but they will listen to you - their customer.