NECRO here, but this solved my problem after I got the ROKU's working but then my Android devices died.
What I did was to block 8.8.8.8 and 8.8.4.4 for the DHCP pool on my router(as ROKU can only get an ip from DHCP and not static) and then set a static IP along with the unotelly DNS servers on all Android devices. Netflix US working on all devices now
Pro_Tip: always fully reboot a device when changing DNS in order to flush DNS records or else it will still fail to work - learnt this the hard way