VPN with tethering strange behaviour between USB and Wifi with streaming

VPN
1

Hi there. So basically I set up a VPN on an old Samsung phone to get USA content. I’m able to use it but I got a strange behaviour. If I try to use/share the WiFi connection (so my home fiber connection) with USB tethering to my TV (LG OLED supports USB tethering) and I use the streaming app on the TV I can browse through the menus, even watch the previews of the movies on the movies info page etc. But If I try to actually watch something I just get a black loading screen and then an error.

Instead if I use the VPN with WiFi tethering, so I’m using my mobile data, the streaming starts!

Why is it doing that? What’s different between mobile data shared with WiFi and the home fiber shared with USB if the VPN is always the same? To the point that the actual streaming is blocked with one method but not with the other?
I’m using VPN hotspot app on a rooted Samsung phone.

2

At least on my S21 it’s only the phone that uses the VPN, other devices connected via internet sharing are routed as usual traffic and not through the VPN. I use the built-in sharing and the phone is stock; why are you using a hotspot app?

3

The app is called like that. It needs root access exactly to “route” the VPN even to other devices that connect to the phone. But I’m having that strange issue. I don’t have lot of data on my mobile plan so I thought I could use the USB tethering that “take” the data from the home wi-fi, but the streaming app doesn’t load anything apart from the menus.

4

But it works just fine if I use the same VPN, set wifi hotspot with mobile data.