diff --git a/configs/sim/README.txt b/configs/sim/README.txt
index 235f42c0e4..b4ec61055f 100644
--- a/configs/sim/README.txt
+++ b/configs/sim/README.txt
@@ -92,8 +92,20 @@ nettest
     cd <nuttx-directory>/tools
     ./Configure.sh sim/nettest
 
-  NOTE: The NuttX network is not, however, functional on the TAP
-  device yet.
+  NOTES:
+  - The NuttX network is not, however, functional on the Linux TAP
+    device yet.
+
+  - As of NuttX-5.18, when built on Windows, this test does not try
+    to use the TAP device (which is not available on Cygwin anyway), 
+    but inside will try to use the Cygwin WPCAP library.  Only the
+    most preliminary testing has been performed with the Cygwin WPCAP
+    library, however.
+
+    NOTE that the IP address is hard-coded in arch/sim/src/up_wpcap.c.
+    You will either need to edit your configuration files to use 10.0.0.1
+    on the "target" (CONFIG_EXAMPLE_NETTEST_*) or edit up_wpcap.c to
+    select the IP address that you want to use.
 
 nsh
   Configures to use the NuttShell at examples/nsh.  This configuration