I just saw that i have a vlan/iptv setup that I can apply as a bridge on the guest network the tv is on. That seems right ?

I think netgear makes the guest network a subnet.

Im going to look into a vlan with all exceptions. It's a nighthawk router so I think it has those features. Haven't gotten around to putting dd wrt on it yet

If you're worried about your IoT devices on your LAN the problem isn't necessarily that they can access WAN but rather that there's a security vulnerability and that they can be accessed by the WAN. Once a device is compromised and attacker can then use it as a "beachhead" to access other devices on your network.

So for example, with my setup every IoT device is on a separate VLAN (the guest network acts similarly) which can't get access to WAN, can't be accessed from the WAN and can't initiate any network calls to any other VLAN. Now my primary VLAN can talk to my IoT VLAN, and IoT can talk back, it just can't start the communication.

This does pose a problem for TVs though that need to talk to Jellyfin as hinted at in the original post. So what you could do is create a specific firewall rule that allows the TVs to at least initiate communication to Jellyfin but not any other device on your primary VLAN. This will probably require a more sophisticated router though than most of the consumer ones out there. Just be mindful that if n IoT device is compromised they can then try to attack the jellyfin server to jump to your other VLAN and then the rest of your network.