This is basically just a repost of the same issue I had when Karmic Koala launched
Ubuntu 10.4 (Lucid Lynx) launched today and I figured it was time to do an install from scratch onto my Dell D830 Latitude laptop. Everything went quite smoothly but when it started up I noticed two issues:
Problem 1: No wireless
I know the Broadcom card inside the laptop isn’t the greatest, but the last two Ubuntu releases it has worked out of the box. The following command enabled the card after a reboot:
sudo apt-get install bcmwl-kernel-source
Problem 2: Really slow DNS lookups (because of IPV6)
As documented on Launchpad, there still doesn’t seem to be an official fix. Strangely disabling IPV6 in /etc/sysctl.conf didn’t solve anything, however disabling it in Firefox at least fixes the issue in the browser. Just type about:config in the address bar, and set network.dns.disableIPv6 to false.

May 1st, 2010 at 2:16 pm
Thanks for the network.dns.disableIPv6 tip. But I think you mean “true”
May 9th, 2010 at 3:33 pm
THANK YOU for the Broadcom Wireless
one line solved many nights of searching the internet
sudo apt-get install bcmwl-kernel-source
Thank you again … Keep the good working on.
May 9th, 2010 at 3:35 pm
Don know why Ubunto does not include such thing from the beginning
is it hard to be considered ? 10.04 without this solution?
May 19th, 2010 at 7:42 am
The ubuntuforum is full of complaints about WiFi speed, and it’s not hardware related, at least not to a single chipset. As it seems to me it is a WiFi subsystem or even kernel regression.
There also seems to be an IPv6 issue, but as has already been noted, simply disabling IPv6 does not help. I narrowed down the problem, and in case you connected by WiFI please try the following:
When speed is slow: disable WiFi
re-enable WiFi and wait for re-association with AP. Is speed back to normal?
Also see http://ubuntuforums.org/showthread.php?t=1473022&page=3 and http://ubuntuforums.org/showthread.php?t=1487039
If it has helped, it won’t last for long, speed drops back to painful slow after some time.
Consider assigning yourself to
https://bugs.launchpad.net/ubuntu/+source/bcmwl/+bug/581936
to raise awareness.
May 19th, 2010 at 10:01 am
Hey Johann, thanks for the reply and those suggestions! It turned out my IPv6 problems were caused by my router however, I documented a fix at http://jetpackweb.com/blog/2010/05/05/netopia-routers-slow-dns-and-ipv6/
May 20th, 2010 at 12:05 am
The ubuntuforum is full of complaints about WiFi speed, and it’s not hardware related, at least not to a single chipset. As it seems to me it is a WiFi subsystem or even kernel regression.
+1