127.0.1.1 is not the address of systemd-resolved, as you noted; it's the address used by dnsmasq. It sounds like your network-manager config is pointing to dnsmasq, which is no longer the default in 17.10, and should have been dropped from your config on upgrade from 16.10 to 17.04. Can you please attach the /etc/NetworkManager/NetworkManager.conf from the affected system?
127.0.1.1 is not the address of systemd-resolved, as you noted; it's the address used by dnsmasq. It sounds like your network-manager config is pointing to dnsmasq, which is no longer the default in 17.10, and should have been dropped from your config on upgrade from 16.10 to 17.04. Can you please attach the /etc/NetworkMan ager/NetworkMan ager.conf from the affected system?