LAN performance issue

I own a Google Chromecast with Google TV and I have a strange issue which I can’t resolve. 

I use Ugreen Ui-gno/re-d70301 Type-C hub for storage extension and LAN connectivity. When I perform a speed test (with Analiti app) I get 300/95 Mbps which is more than enough for my needs. I get even higher numbers when I’m connected to WiFi but I chose to stay with LAN as it’s more reliable connection. All works perfectly without any problem except one. I use a certain streaming service, it’s server located in Netherlands and when I’m connected to LAN and I perform a speed test (Within streaming service’s app), I get around 20 Mbps which is not enough for smooth 1080p streaming and I’m switched automatically to 720p. When I disconnect from LAN and switch to WiFi, I get 60-70 Mbps to thei server and I’m able to watch 1080p content without any problem. Basically, I can use WiFi for streaming but I wonder why I get slower performance to their server when connected to LAN? It’s a shame to have a wired, stable and reliable connection and not using it :-)

Maybe you’ll be able to solve this mystery.

Thanks in advance,

Michael.