There were some changes to the network manager, ConnMan. These are still in the staging repository as they’re experimental. There’s some discussion here: Problem with resolv.conf on NFS root install since march update - #21 by sam_nazarko.
Please run these commands:
ls -l /etc/resolv.conf
dpkg -l | grep connman
sudo rm -f /etc/resolv.conf
reboot
And paste the output. The first two commands will give me some information to see what’s going on; and the last two should resolve the issue for you.
Cheers