As this seems to be an issue with the PC itself, please make sure your device's operating system is up-to-date. If you're using a VPN, I would recommend bypassing it and then attempt to upload these files for troubleshooting purposes. The age of your device, software, and operating system versions, the presence of viruses and malware, and the number of simultaneous applications running can all have an impact on performance.
Cox does offer a comprehensive protection plan that covers advanced troubleshooting for your devices.
www.cox.com/.../cox-complete-care.html
-Kevin M. Cox Support Forum Moderator