Psn sign in error.

Hello,
I brought my ps3 over to my friends house to game out. Connected to the internet fine but would not login to psn. After I brought it home when it has worked before. Still having the same psn login error. Like I'm able to connect to netflix and use the internet just not sign to psn. And ideas? I tried disabling the media server nothing. I tried different DNS codes nothing. Now may not have had a good DNS code but I did try it. I tried unplugging my router. Nothing.