DNSSEC problems in Ubuntu 17.04

I have installed Ubuntu 17.04.
In the installer, I connected to a wifi, but the installation process could not connect, saying DNSSEC validation failed. The same situation was in the installed system.

I found an article recommending to turn of DNSSEC: sudo gedit /etc/resolv.conf and add DNSSEC=off.

I understand the value of DNSSEC, but why it's not working in Ubuntu right away? Even the Ubuntu servers couldn't be contacted by the installer, which, to me, seems like a blocker for releasing the version.

So I assume this is triggered by my local conditions? How? How can I make DNSSEC work? The article recommended getting rid of systemd-resolved and installing Unbound.