Intermittent internet on Ubuntu 12.04, continuous on Windows

[alpha1]

Yes.
I was using Ubuntu 11.10 till one week back.
No issues at all.

However, last week I made a clean install of Ubuntu 12.04
The strange problem is that I am able to connect to internet most of the times, however, sometimes I am not able to open any page.
I thought the problem is with my ISP, however, if I boot to Windows I am able to connect easily.

The internet drops in the middle. I have tried removing the ethernet connection. and doing automatic ethernet from the network manager icon.

I observed something ultra strange! just few minutes back.
I booted to Win - made connection to internet (I have to login to the ISP page). REbooted, logged to Ubuntu and was not able to open any page on Firefox or Chrome.

Manually removed the ethernet connection from network manager. Did auto ethernet.
Was able to see the ISP's login page now. Logged in, opened few pages.
Meanwhile, the update manager opened sayng there is some 90 MB update.
I clicked to proceed.

The update was downloaded.
However, meanwhile (while the updates were getting downloaded) I was not able to open any page in the firefox or chromium!
How is this possible?


What can be the possible problem?
(my IP is dynamic)
I have tried pinging google.com, but no ping happens during this time.3
However, the ping to my gateway happens.
And remember, I was able to download the update all this while!

[alpha1]

Error message in FF:
Server not found

Firefox can't find the server at forums.linuxmint.com.

Check the address for typing errors such as
ww.example.com instead of
www.example.com
If you are unable to load any pages, check your computer's network
connection.
If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.



Error message in Chromium:
This webpage is not available
The server at www.google.co.in can't be found, because the DNS lookup failed. DNS is the network service that translates a website's name to its Internet address. This error is most often caused by having no connection to the Internet or a misconfigured network. It can also be caused by an unresponsive DNS server or a firewall preventing Google Chromefrom accessing the network.
Here are some suggestions:
Reload this webpage later.
Check your Internet connection. Restart any router, modem, or other network devices you may be using.
Check your DNS settings. Contact your network administrator if you're not sure what this means.
Try disabling network prediction by following these steps: Go to the wrench menu > Settings > Show advanced settings... and deselect "Predict network actions to improve page load performance." If this does not resolve the issue, we recommend selecting this option again for improved performance.
Add Google Chrome as a permitted program in your firewall's or antivirus software's settings. If it is already a permitted program, try deleting it from the list of permitted programs and adding it again.
If you use a proxy server, check your proxy settings or contact your network administrator to make sure the proxy server is working. If you don't believe you should be using a proxy server, adjust your proxy settings: Go to the wrench menu > Settings > Show advanced settings... > Change proxy settings... and make sure your configuration is set to "no proxy" or "direct."
Error 105 (net::ERR_NAME_NOT_RESOLVED): Unable to resolve the server's DNS address.

[alpha1]

BTW the problem occured again, while I was posting the thread.
I created the thread and the internet dropped off.

I regained it back in few minutes.
Any idea why it happens?

Here is the network connection detail from windows:


linux:



Oh, and once the connection dropped - I tried the update service as well as snypatic, but this time the download did not take place.


I am really puzzled, since there was no such problem in Ubuntu 11.10
:'(

[heavy metal]

Have you tried installing "Wicd" and uninstalling "network manager"???

[alpha1]

No.
But isnt wicd for wifi etc?

I hadn't had problem with nm-applet till now.

I hope after installing wicd I don't get ethernet problems ...


[EDIT]
ok so I have nearly got to the bottom of this problem - looks like some DNS server issue with my ISP.
When I was not able to open any site I tried pinging google.com
No ping.
I tried pinging 74.125.236.71
Ping happened.
And I was able to open google.com on my browser by writing the IP address.

But the problem automatically resolves in 5-10 minutes.
But why am I not facing this problem in Windows?


Something to do with the "lease obtained and lease expired" thing in the screen shot above ?

[alpha1]

PROBLEM SOLVED:

The error is becuase of the changes done in Ubuntu 12.04
http://www.stgraber.org/2012/02/24/dns-in-ubuntu-12-04/
"Using dnsmasq as local resolver by default on desktop installations"

AS usual Ubuntu folks have brought out a feature that has broke the functionality:
https://bugs.launchpad.net/ubuntu/+sour ... bug/989900

Resolution is simple:
gksudo gedit /etc/NetworkManager/NetworkManager.conf
comment the “dns=dnsmasq” line (hash symbol)
sudo restart network-manager

(i restarted the pc just to be sure)

I shudder to think what would happen to a new ubuntu user, this they call a long term support version: ready to take on Windows and MAC OS?
What a bunch of idiots at Ubuntu ...

[heavy metal]

@Alpha1:
Tell me something, this happens to you if you use wired or wireless connection or both?

[alpha1]

This was wired.

No idea about wireless - India ain't that developed yet to give true unlimited broadband on wireless.

[Gutknecht]

This issue affects wireless as well. I'm still trying to resolve on two of my systems. I tried the comment out line, but it didn't seem to help, but I may not have restarted. I will give it a go and see if it will fix...

[dholz]

I've run into this several times, I removed the supplied network manager and installed Wicd network manager- problem solved

[larryorth]

I have never used the forum before. I am new to linux. This problem has plagued me for weeks. Thank you so much for the post. It seems to have resolved my connection problem. Please post this for everyone to see. I am 63 and at my age time is of the essence. Thanks again. solution is below!!!

Resolution is simple:
gksudo gedit /etc/NetworkManager/NetworkManager.conf
comment the “dns=dnsmasq” line (hash symbol)
sudo restart network-manager