

As others have mentioned, the websites tend to be limited both by resolution and functionality.
My TV supports CEC(most do these days) which will pass the remote input onto the devices connected to it, like a computer. Which means with Plasma Big Picture I can navigate with my remote, and any app that supports navigation with simple arrow key input would work great.
Unfortunately, the streaming websites, last time I tried, absolutely suck at that and assume you are navigating with a mouse.
You are probably correct that the firewall is the culprit. Good suggestion.
I realize disabling the firewall for testing is OK, but I recommend looking up what it takes to open the ports or app in the firewall instead. I’ve spent my whole career running into and fixing instances where techs disabled firewalls for “testing” and never re-enabled them.