Panasonic Smart TV - Issues with streaming from a website not an app

Just wondering if folks have seen something similar.
My uncle has a Panasonic smart tv, i'm not sure of the model but its about 5 years old or so.

It is connected to the internet through a network cable directly to the router in the house, and he can browse the internet on it. However, there is something a little strange on it.

Last Saturday he signed up to access Munster to watch the Munster v Argentina match, but while he could get it to work on his tablet, it would not work on his tv. I went to his house on Sunday to see if i could figure it out, but when signing into the access munster website through the inbuilt browser on the tv, it wasn't accepting his username/password combo.I was also able to sign into his own netflix account using the TV inbuilt apps, so there are apps working on the tv suggesting there is no fault with the device itself.

I tried it on my own Samsung tv at home and was able to access the website and start playing the match using his username and password, so his account is set up, and is working on a different smart tv.

I'm just wondering if there is something in the Panasonic setup that prevents accessing a website (not an app). I havent tried accessing youtube through the browser on the tv yet, that's part of my plan for tonight