ummm all routers show what's connected to it with ip addresses

usually it's 192.168.1.1 - or 0.1 - for dlink/linksys/airport express
you can look at what's connected to your router from your router's ui config page...
next time, make your dns-321 a static ip so you won't forget it...
plus - when you go into the dns-321 object, other than volumes is the web_page folder, inside is an html file - that'll take you to your dns-321 config page (aka ip number)