I was able to ping and telnet (or otherwise communicate to) the handreader, but I cannot connect via the SchlageCommDiags utility

Resolution: If you used the default installation, you can find the SchlageCommDaigs icon at:

Start -> All Programs -> Recognition Systems -> RSI .NET 2.0 DLL -> SchlageCommDiags.exe

If no modems are detected, you will see a pop-up message: "You don't have any modems installed"; just click 'OK' to get to the actual utility.

if you are unable to connect to a handreader or fingerkey, please check the following:
 - Reader Type: select Fingerprint Reader if youhave any of the Fingerkey models (DX2000, DX2100, DX2200)
                     or select Hand Reader if you have any of the Handpunch or Handkey models
 - select the tab that matches your communication method:
   if you select ethernet, please make sure the Reader Address in the next section below, is set to "0" (zero)
 - for the Reader Address, enter the same number that is programmed in the reader as its address (password menu 2 -> set address)

To run the connection test, click on "Contact Reader"

If you are able to ping and telnet  (or otherwise communicate to) the handreader, but I cannot connect via the SchlageCommDiags utility:
run it as 'admin': go to the SchlageCommDiags.exe  icon, right-click on it, then select "run as..." and select "admin"

SchlageCommDiags User Guide