Phones, laptops and televisions use different routes
The device doing the playback needs the intended connection. A VPN on a laptop does not automatically cover a television on the same Wi-Fi. Before subscribing, check the provider's current instructions for the exact platform and app version you will use.
ITVX itself runs on most televisions. ITV's device list includes Amazon Fire TV devices, Android TV and Google TV, Apple TV on tvOS 18 or later, Freely, Freesat and Freeview Play, LG smart TVs from 2016 and Samsung smart TVs from 2017. Whether a VPN app will run on the same television is a separate question, so check the VPN provider's current support pages for the exact television or streaming device before subscribing.
Casting is a common source of confusion. In some arrangements the phone controls playback while the television or streaming device downloads the video itself. The phone's VPN then says little about the route the video actually takes.
A router-level arrangement can cover supported devices through the router, but it depends on compatible hardware, firmware and configuration. It can also affect everyone else using that network. Do not plan to alter a hotel or rented property's router as though it were your own equipment.
At home, a router needs a built-in VPN client, and providers publish configuration files for manual setup; NordVPN's support pages explain where to find its files. A router does the encryption on a small processor, so expect it to be slower than the same VPN running on a laptop. A laptop can also share its VPN connection, through Mobile hotspot in Windows or Internet Sharing on a Mac, but it has to stay switched on for the television to keep its connection.
For ordinary travel, a prepared phone or tablet is often the simplest way to carry eligible downloaded programmes. It also avoids discovering that the television's app store, supported apps or connection options differ from the setup at home.