You said you are using your external IP, but you should be using the internal IP address of the computer running Dr.DNS on your local network. Here is impulse's instructions on using dr.dns for connecting to PSO. The setup instructions are the same for Quake 3, I just added another line into the redirect.txt file to redirect the q3 master server to the one hosted on the dctalk game server. He did mention you need .NET framework installed and your computer should have a static IP address.I entered my external IP as my Primary DNS
http://dreamcast-talk.com/forum/viewtopic.php?f=3&t=274
For Dr.dns instructions please read on past v1.
1b. PSOv1 NTSC/U via BBA:
You will need the following tools before you begin:
PSOv1 NTSC/U.
PC with static IP address go here to find out how: http://portforward.com/networking/staticip.htm
Dr. DNS: http://dreamcast-talk.com/uploads/pso/drdns.rar
[Need one of these to configure DNS to connect. Easiest to obtain is the XDP web browser:
XDP Web Browser for DC: http://dreamcast-talk.com/uploads/pso/x ... dition.rar
Or
PSOv2 NTSC/U or J ]
Pre-Setup Clarification:
It is true that the BBA is not supported by PSOv1 natively, and if you try to use it, you will get BBA is unsupported and it will refuse to go online. This is, however, not actually the case. If you load USv2 and select the website option, you can configure your Dreamcast for static IP. Once you do this and click save, you can return to the title screen and power off and use USv1. Once the BBA has been configured with USv2, USv1 will support it. When you connect online with a BBA instead of a modem, all the text banners are missing and you see only the star screen until the game connects.
You must first set up your PC prior to attempting a connection. To start, you must load Dr. DNS and make sure the redirect.txt text file is set to DC-Talk's IP address (dctalk.ath.cx) like this:
*NOTE: You must have .NET framework installed on windows to run Dr.DNS:
Download here for 32 bit(x86)
Download here for 64 bit(x64)
dctalk.ath.cx dctalk.ath.cx
pso-dc.ath.cx dctalk.ath.cx
gsproduc.ath.cx dctalk.ath.cx
schthack.ath.cx dctalk.ath.cx
game01.st-pso.games.sega.net dctalk.ath.cx
pso.dream-key.com dctalk.ath.cx
pso01.dricas.ne.jp dctalk.ath.cx
game04.st-pso.games.sega.net dctalk.ath.cx
master.pso.dream-key.com dctalk.ath.cx
Once finished, make a shortcut on the desktop and rename it to PSO DC-Talk. Click on the shortcut to run Dr. DNS. When it is done loading, make sure the office is open (see example 1 below) is displayed. This means the PC phase is complete. Make sure your PC has a static IP address go here to learn how to do this: http://portforward.com/networking/staticip.htm. Choose your operating system from the bottom of that page. Also make sure that your Dreamcast is connected to the same router/switch/hub that your PC is.
EXAMPLE 1
Attachment:
connect-DC-Talk.JPG
connect-DC-Talk.JPG [ 54.17 KiB | Viewed 1627 times ]
Now you need to find your IP address. For those who do not know how to do this, go to START, then select RUN. In the box, type cmd then click OK. Now type ipconfig then hit the Enter key. The IP address will appear. Write this down for use in the Dreamcast's bios flash of this setup.
Now, get out the Dreamcast and set up the BIOS. To do this, boot up with PSOv2 NTSC/U or J, XDP or PW 3.0. Go to website setup and enter the PC's IP address under the DNS section only (do not change any other settings). Make sure you save before powering down.
. It does seem at the moment that EVERY Dreamcast Q3A server is currently down (including DC-Talk's), but that has nothing to do with not being able to connect. I still haven't entirely figured out DC-Talk's Master server, but even without it, I was still able to connect to individual servers. 
