TP-Link Archer D2 - Intel (Lantiq) VRX318 (Lantiq ARX368 ADSL2 + ) based has 64 mb RAM / 16mb rom AC750 (300 + 433) 1 USB 2.0: and should be very friendly for open source including ADSL/VDSL.
GPL http://static.tp-link.com/resources/gpl/ArcherD2_GPL.tar.gz