I have the wpcrt wifi 6 router setup with surfshark and it works great but my IPTV service will not connect unless I still use the app on Nvidia shield.
What app are u talking about?
using the router test your IP here>>> https://dnsleaktest.com/
then without you router test your IP with the app. Im thinking that its the server you are connected to. Take a note of the location the app is connected to and then get the router credentials from surfshark for that location and insert in the router. re-test.
Try changing your location, I’ve had IPTV services that wouldn’t connect if I was using a Canadian server but would with a US one.