For a local network with 256 local addresses, you can enumerate them and use the Web component to issue GET requests one at a time.
Keep the addresses in a list, test them one by one, and deplete the list as you solve each address, to avoid a hullabaloo .
The Web component has a timeout event, recently added. Or you could add your own Clock component and set a watchdog timer to catch indefinitely slow responses.
This assumes your devices respond to web requests.