Login problem: Unable to connect to server

Hi, SL techies:

I just signed up yesterday. Installed newest SL version (1.13.1), and am trying to login.
This is my very first try, and I got this error:

Unable to connect to server.
Could not resolve domian name: userserver.agni.lindenlab.com.
Please check your network connection.

As you can see, my network connection should be fine. Otherwise I would not be able to send this question. I have tried many times and still got the same login error.

Is this simply because server is down or something is wrong with my setup?

Appreciate any help.

firewall/router/virusprog~trojan blockers/ can silently block Secondlife, be sure to add them to allow list to connect.

This happen alot , and just about every update some get their secondlife.exe blocked cause version is changed and get silently added to block list on some programs.

Thank you very much, Thili.

Maybe something is wrong with my router and firewall configuration. After I played a little with my router and disabled my firewall, now I get a different error:

Unable to connect to Second Life. The system may be down. Please try in a few minutes...

This thing seems to have a fairly long learning curve.