Couple possibilities come to mind...
DNS not resolving 'cuz you are querying upstream DNS before internal...
Users > Resource Policies > select NC role and check if "Search the device's DNS servers first, then client" selected.
You home network range is over-writing your intranet.
ipconfig /all, netstat -rn, and the IP of the internal server should yield some clues.
Of course there's a lot of other potentials like restrictions from source IP, access to apps, etc. but the above two are the usual errors.
