According to THIS SITE

these games are able to navigate the broadband adapter without first priming the VMU or Dreamcast with a browser disc.

# POD Speedzone - US/NTSC
# Quake 3 Arena - US/NTSC
# Unreal Tournament - US/NTSC
# SegaAM2 BBA Config Tool (Outtrigger/Propeller Arena)

I'm currently online in the Quake III Arena Game browsing MANY (to my total surprise) available matches.

most useful piece of info from the article I noticed:
"To have your Dreamcast automatically retrieve an IP on the local network, set the IP, Subnet, Gateway, and DNS entries to "0.0.0.0". This is the standard configuration for accessing a DHCP server, which will automatically assign your Dreamcast with the necessary information upon connecting."

When I used Quake's multiplayer game option to test this out, I just left the ISP provider info completely alone. Didn't even look at it.
I simply assumed since Quake 3 Arena supports DHCP and that I am behind a router, it would detect the settings. And it did.
Which is the whole point of DHCP.

I also have unreal somewhere I think, and will see if that works the same.
According to my previously stated source, this SHOULD save your modem and connection type "TO THE DREAMCASTS INTERNAL MEMORY"? not sure.
We'll see.

Hope this helps someone out.
I have no idea if this is old or common knowledge.