I'm thinking it's maybe a firewall rule. I'm not sure. It's just strange that all my network traffic goes through the router and can resolve anything, but nothing from the router itself can except for the `host` command.
root@core:~# curl -v -6 http://www.google.com * getaddrinfo(3) failed for www.google.com:80 * Couldn't resolve host 'www.google.com' * Closing connection #0 curl: (6) Couldn't resolve host 'www.google.com' root@core:~# update webproxy blacklists Warning: No url-filtering blacklist installed Would you like to download a default blacklist? [confirm][y] curl: (6) Couldn't resolve host 'ftp.univ-tlse1.fr' Unable to download [ftp://ftp.univ-tlse1.fr/pub/reseau/cache/squidguard_contrib/blacklists.tar.gz] root@core:~# curl -v -4 http://www.google.com * getaddrinfo(3) failed for www.google.com:80 * Couldn't resolve host 'www.google.com' * Closing connection #0 curl: (6) Couldn't resolve host 'www.google.com' root@core:~# host google.com google.com has address 172.217.3.174 google.com has IPv6 address 2607:f8b0:400a:808::200e google.com mail is handled by 10 aspmx.l.google.com. google.com mail is handled by 50 alt4.aspmx.l.google.com. google.com mail is handled by 30 alt2.aspmx.l.google.com. google.com mail is handled by 40 alt3.aspmx.l.google.com. google.com mail is handled by 20 alt1.aspmx.l.google.com.