Downloading over the internet of 400 mb files takes 20 minutes or it crashes sometime in windchill

Version: Windchill 12.0

Use Case: We are trying to download over the internet a file size of 420MB, it takes more than 20 minutes to download or sometimes it crashes, whereas same file downloads with in few second when connected to intranet.

Description:

We are trying to download over the internet a file size of 420MB, it takes more than 20 minutes to download or sometimes it crashes, whereas same file downloads with in few second when connected to intranet. is there any configuration to check for from windchill end or else its something we have to with the network side.