There's a worrying trend (I'm looking especially at you, UPC), where the ISP insists that the CPE device must be in router mode, and not in bridge mode. The UPC

There's a worrying trend (I'm looking especially at you, UPC), where the ISP insists that the CPE device must be in router mode, and not in bridge mode. The UPC's current excuse is, that their devices come preconfigured for DS-Lite and that most customers would be unable to configure their own routers for that. Together with the fact, that you are getting a single /64, it means that you cannot place another router behind their router. (And for IPv4 part of the DS-Lite, no, they don't support PCP).