dhclient is trying to get ipv4 info through an ipv6 device

Or at least is the analysis I did, exact situation is as follow:

- Arrived in a friend's appartment, phone (Android) connected to internet OK

- Opened the laptop, NetworkManager showed the attempt to connect, then finished saying "connected", but the icon wasn't right, and I didn't have internet in the computer

- Wife's phone (android) connected ok (just mentioning this to mark the fact that the router had free IPs, etc.)

- I started debugging, couldn't make it work. Finally, I hardcoded the IP, mask, gateway, and DNSs, and everything worked ok, so it leaded me to distrust dhclient in the process

Attached are the full syslogs from the connection attempt, with the info from devices and routes after leaving it to connect.

Thanks!

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: isc-dhcp-client 4.3.1-5ubuntu3.1
ProcVersionSignature: Ubuntu 4.2.0-23.28-generic 4.2.6
Uname: Linux 4.2.0-23-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Jan 19 14:33:00 2016
DhclientLeases:

InstallationDate: Installed on 2015-10-26 (85 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: isc-dhcp
UpgradeStatus: No upgrade log present (probably fresh install)