Operation timed out (IPv6 issues)#
We recommend you fix your IPv6 setup. If that is not possible, you can try the following workarounds:
Workaround Linux:
On linux, it seems that running this command helps to make ipv4 traffic have a higher priority than ipv6, which is a better alternative than disabling ipv6 entirely:
sudo sh -c "echo 'precedence ::ffff:0:0/96 100' >> /etc/gai.conf"
Fonte : https://getcomposer.org/doc/articles/troubleshooting.md