"The requested operation requires elevation" is because you didn't run the command prompt as an administrator. You can right click, then choose run as administrator to solve this problem. ipconfig /flushdns may do the trick.
I've tried renewing it via command prompt but an error also comes up
"The requested operation requires elevation" to the command ipconfig /renew AND ipconfig /release
Anybody know what I can do next to fix this? I'm completely stumped
I would try powering down your Cable Modem for around 2 minutes. Dissasemble everything, than power it up again and see if it works. Try another ipconfig /release-reboot-Ipconfig/renew. If that doesn't work call your cable modem company and let them know or it might say a server is down in your neighborhood and they are resolving the issue!