Hey guys, thanks so much for reaching out. Here's an update on the situation...
So looking at the network setup, it doesn't look like there's anything 'in front' of the nest router besides the "ONT" sitting outside my house connecting me to the fiber. So I don't have any ISP router or anything that I have access to. To see if double NAT could be the issue still, I removed all the Nest mesh endpoints, and tried configuring my Nest Router to be in bridge mode to see if that would make a difference. However, trying to set it up in bridge mode fails with a generic error message saying that it failed to configure the router to bridge mode. According to the Google documentation you linked, it won't be able to go into bridge mode unless there is another router upstream, so I think that rules out the double NAT issue?
I was looking further into the issues I'm seeing with Disney+ specifically, and opening up the network traffic in the dev-tools of my browser, I'm seeing that I get a bunch of CORS errors showing up when I try and load the site (https://www.disneyplus.com/home). Comparing it to when I unplug my router from the wan and just plug my laptop straight into that cable, it sends those same requests just fine (and the site works fine). The difference is the working request (when not connected to the Nest Router) I can see sends up the appropriate 'Access-Control-Allow-Origin' header in the request, whereas when I'm connected to the Nest router it's missing (and hence throws the CORS error). I can't seem to edit / find any settings on the Nest Router related to security, and I'm not quite sure why the 'Access-Control-Allow-Origin' headers wouldn't be present (somehow they're being removed by the Nest router it would seem).
I tried adding a screenshot of the errors for context, but looks like you can't do that on these posts unfortunately. @Alex_S @olavrb
