I had a customer that needed to access Saved Filing information from previously e-filed payroll reports. However, whenever they tried to open the hyperlinked report inside of Quickbooks, they were greeted with a 404 error.
The fix for this issue is quite simple. Simply map a drive letter to the server instead of accessing the company file via UNC path. This will let your browser know the link is a file location and not a HTML file.
Here is the link to the original post on the QuickBooks Forum. Shout out to BettyJaneB for this solution.