the "web_page" is not actually a drive - it's basically a link to your dns-321's config ui page (however, your ip address for your dns-321 could be changing)
what you need to do:
first, is basically a good idea to assign or reserve an ip address just for the dns-321 in your router.... so that it will never change - that way whatever link or drive you create/map it'll point to the correct ip address of the dns-321
second, if you are on windows - your windows network could be the culprit, check your windows computer and network for any sleep/awake times/schedules, hibernations, and also check your network card's power status such as "always on" - "allow to sleep" etc....
in mac - it just works

third, double-check your dns-321's power management features, do you have it set to sleep after 5-minutes?
let us know what happens! and good luck!
