I get a similar message when going to m.facebook with my Windows Mobile phone on Sprint. No problem with my S4 Mini. And it's not really a problem on WinMo either, becuase there's a choice to allow the site in spite of the certificate issue. What is written on the button at the bottom left of the white area on your screen shot's error message? It's too small for me to read. Oh, wait. If it says "Back" then you may have some kind of firewall setting that needs changing.