This might not apply to your situation, but here goes.
I also had problems accessing three sites about two weeks ago: Fighting Dolls, Foxy Combat and this forum.
I had just installed Norton 360 with VPN support, and when I disabled the VPN support option all three sites were once again available. I accessed all three with VPN support not engaged, then restarted my device and engaged VPN again, and again I could not access any of those three sites. By restarting my device and not engaging VPN, all three sites were accessible.
So now when I start my device I check those three sites prior to enabling VPN and all is working well.
As I said, this might not apply to your situation, but if it doesn't there still could be a connection with your security suite even without VPN.