I was very frustrated to find no post involving a netflix error (-121) I had on my android phone, and on my kindle fire HD. I figured out the problem and how to fix it! it worked for me and may not work for you.
1.) Go into wifi settings
2.) Go to your wifi and hold it down and select "modify network"
3.)select "advance options"
4.)If "ip settings" says "DHCP" change it to "static"
this were things get weird
5.)change "ip Adress" to what ever is lightly suggested, before you start typing, EXCEPT for the last set of numbers, ie if the suggested ip is 192.168.1.128 change the 128 to a two digit number under 20 like 08, 13 ect. so now in ip adress it is 192.168.1.13 (not exactly that unless the suggested was 192.16.1.128, what ever the suggested is should be the change)
6.)Press save and restart netflix and try again!!
Hopefully this works if not ask questions we can make this problem not be one!!
1.) Go into wifi settings
2.) Go to your wifi and hold it down and select "modify network"
3.)select "advance options"
4.)If "ip settings" says "DHCP" change it to "static"
this were things get weird
5.)change "ip Adress" to what ever is lightly suggested, before you start typing, EXCEPT for the last set of numbers, ie if the suggested ip is 192.168.1.128 change the 128 to a two digit number under 20 like 08, 13 ect. so now in ip adress it is 192.168.1.13 (not exactly that unless the suggested was 192.16.1.128, what ever the suggested is should be the change)
6.)Press save and restart netflix and try again!!
Hopefully this works if not ask questions we can make this problem not be one!!