I have been using an ISP-provided ADSL modem/router combo (not rented) for a while, and had it configured with an OpenVPN server... one day it stopped working, and when I went to investigate found that the ISP had disabled that functionality remotely. No warning, no communication, just gone. Couldn't roll back the firmware or disable TR069 either. Bastards.

TR069 is useful for the ISP but a blight on users. I haven't gotten around to it yet but I'm changing over to bridged mode and going to get a nice OPNSense or similar appliance to handle the firewalling and PPPoE stuff.