Here's what could be happenning:
You port hasn't been opened up in the Raspberry Pi's Firewall. Now, I don't know how to add a rule to the Firewall but after some help and a little research, this what I found:
Log into the Pi through PowerShell
Enter-PsSession -ComputerName MyRaspberryPi-Credential MyRaspberryPi\Administrator
After that, manually add the Firewall opening of the port you're using, should be port 8080 as per your description.
netsh advfirewall firewall add rule name="Raspberry Pi Webserver" dir=in action=allow protocol=TCP localport=8080
And, you should, now, be able to access the port on your Raspberry Pi!
Plus, It seems like this issue with the Firewall not being opened is actually a known issue by Microsoft already. They write about it in their Release notes for the Insider Preview version 14295, which is the OS you're most probably using on your Pi: http://ms-iot.github.io/content/en-US/win10/ReleaseNotesInsiderPreview.htm