I have also tried resetting network connections to no avail. From a google it looks like it could be something to do with DHCP but I really don't understand why it would only effect one PC so don't really want to start messing with that!
I'm having difficulty understanding why it is just a problem with upload and not download. If it was a DHCP/IP addressing issue it would affect download as well as upload.
I have fixed it, it would seem it was a Windows update and is to do with my Killer E2400 Gigabit Ethernet Controller. Although I didn't have any of the killer software installed on my PC I did have the KillerNetworkService.exe service running. I downloaded KillerSoftwareUninstaller which has scanned my PC and done the trick in removing the problems services
Thanks everyone for your assistance!