Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Inspect the exact advertisement field
An IPv6 host can learn prefix information and default router information through Router Advertisements, but those facts are not the same. RFC 4861 states that Router Lifetime applies to the sender usefulness as a default router and not to every option. A zero value indicates that it should not be on the default router list. Other options carry their own lifetime information. An address prefix visible on a device therefore does not by itself prove a usable default route.
Explain an apparently mixed state
For an original conceptual case, a managed router advertises a prefix for local autoconfiguration but does not offer to forward general traffic as a default router. A host may show an address associated with that prefix while lacking the expected default path. Those two observations need not conflict. Preserve the address, route and advertisement information privately with observation times instead of reducing the condition to IPv6 on or off.
Leave configuration changes to the actual design
A network maintainer should check the intended advertisement configuration and applicable device documentation before altering it. Do not invent a default gateway from another subnet or disable IPv6 to hide the symptom. This article explains why separate lifetimes and roles matter in a technical report. It does not provide an attack recipe, establish that a home router is misconfigured, or claim that address allocation alone certifies a working media service.