How to paste into nano from clipboard?
You could try the following two commands to paste from the clipboard. Both of them should work.
The Ctrl+U command only allows pasting text that was copied or cut from within nano itself, hence the reason the command is not working.
Unfortunately, for the specific case when using Vultr console, there seems to be no easy way of using copy and paste. Vultr simply does not support it. An alternative would be to use SSH together with another terminal to connect to the server. If you are on Windows, using putty would work.
SSH Putty windows Shift+right mouse click worked for me with default putty settings.
I successfully used right mouse button to paste from Windows 10 to nano on "Bash on Ubuntu on Windows".