With IPv6 enabled some users experience slow Internet, normally due to browsers trying IPv6 first if that fails then reverting back to the IPv4 stack. If you have a half configured IPv6 setup then you may experience other networking issues, this guide show you how to disable IPv6 on Ubuntu 10.04 / 11.04 and all other current versions see below.
Ubuntu Disable IPv6 via Grub
The following command disables IPv6 using Grub at boot time, and I have found it the most affective.
Find the line:
Replace it with the following line to disable IPv6 on Ubuntu:
Save the text file (see our vi commands page for more vi help) and update grub with:
You are good to go… Reboot and you will have disabled IPv6 on Ubuntu.