in general devices from time to time pretending to be a new device can be preferred as a form of privacy protection E.g. with IPv6 we have enough addresses to

in general devices from time to time pretending to be a new device can be preferred as a form of privacy protection E.g. with IPv6 we have enough addresses to give every device in the world today and for decades to come unique addresses and using devices MAC you can reliably generate them collision free. So you don't need NAT so routers can well only route instead of routing and proxying IP Address/Port. Problem is that leaks a lot of private information. So a schema was added which while upholding the properties allows "randomizing" (and changing over time) addresses. But coming back to the smart TV I don't think this is the case here as it changes the address _far_ to often and it's a UPnP i.e. local network only Id. Furthermore UPnP also advertises devices descriptions so de-anonymizing randomly changed IPs is more then trivial. My guess is the UPnP software module is started anew every few minutes and generates a new uuid every time. This might be due to it not persisting the uuid. Weather that is because they just didn't bother implementing persistent device ids or weather it regenerates it after every time it crashes and it crashes every few minutes I can't say. But it looks a huge lot like a software bug. What also is a 100% a but is that this external device misbehavior can mess up Windows (through I wouldn't be surprised if it isn't just Windows which has problems with that). It means that there is a resource controlled by external events which isn't "bound" which from a security POV is always a terrible idea, even if it might at most cause a DOS attack (not just because DOS is bad but also because it's not rare that people find ways to use DOS attacks alongside other found attack vectors to more reliably succeed).