Well I don't think that his problem is computer-related. He has stated about the DNAS, which is Ps2's Domain Name Authentication services. He must be speaking about his PS2 FFXI. The steps on connection are:
1. The ps2 first checks the PS2 Network Adapter and makes sure that it's connected to a cable modem or Dial-up connection. You have gotten past this, so we can assume that you have the cables connected.
2. The PS2 now attempts to make an internet connection by verifying the DNAS. You are getting a DNAS error, so your problem is in connection to the internet.
If you have a cable modem:
1. Check to make sure the Power, Cable, and (if your modem has it) the PC light. Make sure that those lights are on. On most Cable Modems, the lights will be fully lit. If any of those are not lit, you should know what the problem is.
2. If the lights are lit, check the cable. If you have another cable, replace it to see if that helps. If you still experience problems, power down the PS2 and unplug the cable modem's power supply. Wait for 10-20 seconds, then plug in the cable modem. Give it a minute or 2 to do it's Power on, and then turn on your PS2. I recommend going through the Network Setup that you did when you first got the Network Adapter. If this does not work, and you have another network adapter you can try out, try that...
If you still have problems after trying what I said, contact your ISP... IF you have dial-up, then idk... i am not good @ dial-up connections...
Hope this helps ;)
I hope this helps.