I just read some more of your comments and thought I might properly explain VLANs:
VLANs let you create a whole virtual network within your physical network, there can be upto 4096 of them that can be tagged and 1 untagged per port, the VLAN ID defines which one to use.
A tagged VLAN is often used between routers and switches, so the connected device can pick which VLAN to use, but an untagged VLAN dedicates that port to that VLAN making it appear to the connected device as if it’s the physical network.
Since it’s a whole new network you need some sort of router to route between them.
As a rough example you could have something like: Router --2T–> Switch --2U–> TV, where the T is for tagged and U for untagged. Or replace Router with Pi if you use that, the Pi will access the internet with the (technically untagged) physical network, and route between tagged VLAN 2, meaning you can do everything on the Pi with 1 ethernet port.
Disclaimer: Most of this was learnt from experience so it might not be completely correct.