Well I have a fix for this if anyone has this problem.
I dont know why this works but it clearly bypasses what ever conflict is preventing netflix from connecting.
simply connect your ps4 to a different network and sign into netflix. For me I used my phone as a hotspot and connected to my mobile data. Once signed into netflix, sign out and set your wifi back up and reconnect ps4.
Bingo... you can now connect to netflix and no more bloody ui -800-3.
You are my hero! I tried this and it worked. Very much appreciated, can't say thank you enough.