Netflix has hidden test screens to calibrate your TV — here's how to find them

OK, Quad9 worked. But the Netflix address resolved to
 
I was able to bring up an appropriate pattern on my ROKU based UHD set. BUT - while it displays, nothing actually worked (moving around in the pattern). And even if it did, any thoughts on setting gamma? ROKU UHD sets have Extended Picture Settings you operate from the Roku Mobile App (recently fixed after not working for a couple years on most Android phones).