How to Fix IPv6 apt-get update Error on DigitalOcean Servers

How to fix the "could not resolve" and "failed to fetch" errors when using apt-get update on DigitalOcean Ubuntu servers connected over IPv6:

1. Type the following command: nano /etc/resolv.conf
2. Add these two lines to the end of the file:

nameserver 8.8.8.8
nameserver 8.8.4.4

1. Use CTRL+X to close the editor, type y to save changes, and press enter when the "file name to write" appears.
2. The apt-get update command should work now.

Video: https://www.youtube.com/watch?v=XxbbIcM3Gs4