extra logging info for NAT

Author: carver

p2p/nat.py

@@ -160,6 +160,8 @@ async def _discover_upnp_devices(self) -> AsyncGenerator[upnpclient.upnp.Device,
         except TimeoutError:
             self.logger.info("Timeout waiting for UPNP-enabled devices")
             return
+        else:
+            self.logger.debug("Found %d candidate NAT devices", len(devices))
 
         # If there are no UPNP devices we can exit early
         if not devices: