Hey all.
I had red NAT and I wasn't able to fix it through disabling firewall/antivirus, changing router settings etc. I have cable connection, but since I have a large house, I have couple of routers in there and I was connected to the nearest of it. So, I changed NAT from red to green by purchasing power socket internet adapter.
I've connected to the main router and NAT went green. Same idea if you have wireless. Try to using those.
If it helps you - cheers, if not...