After surfing internet for a while ,then drop the line, an exclamation mark in the local network icon. Using the windows network check, hint:windows cannot communicate dns server. 

Topology

Internet ==>BRAS===>ADSL========>Router==switch==>client computer

                                               (PPPOE)

Configuration

Notebook: 

  IPV4: 192.168.4.29

  mask: 255.255.255.0

  gateway: 192.168.4.1

  DNS: local dns server ip

Switch:

 vlan 4

 ip from 192.168.4.20~192.168.4.253

 ifvlan 4

 ip: 192.168.4.1  mask:255.255.255.0

Route:

  IP: 192.168.1.1

  static route

   destination         mask                                gateway                   status

  192.168.4.0        255.255.255.0                     192.168.1.2                automatic

you have to check the local dns server.  there must be a DNS forwarder on it.

What type of local DNS server do you have?

DNS: local dns server ip shouldn't be there. Rather it should be your ISP Public DNS Address. Or you can try 8.8.8.8 as test and see if that makes any difference.

yes Binu Kumar, it's ISP Public DNS Address setting in my notebook.

But sometimes the line drop, and then i use a RJ45 cable connect my notebook with the Router through Local port. My computer and the Router in the same IP category 192.168.1.x,but i can't log in the Router. Maybe the Router is down. I then restart the Router, i can surfing again. 

 Local ISP Public DNS, Address:202.101.224.69

1. Network monitor will help you to resolve the problem. Wireshark will do the trick for you.

2. Double check the health or your router/ADSL. This problem need not be inside your computer. Other device(s) may help - another computer or mobile phone. Look into log file of router and ask ISP support for cooperation.

3. Sometimes there are weird problems caused by current throughput of entire network.

4. Try to eliminate unnecessary devices - if there is a possibility to connect computer directly to ADSL.

5. Use standard troubleshooting with nslookup and test, if ports are opened - with nmap (and similar).

6. Divide your trobleshooting into two steps - connectivity and name resolution.

7. Make sure that something like QoS does not play the role.

Rgds

Milos

1. Network monitor will help you to resolve the problem. Wireshark will do the trick for you.

2. Double check the health or your router/ADSL. This problem need not be inside your computer. Other device(s) may help - another computer or mobile phone. Look into log file of router and ask ISP support for cooperation.

3. Sometimes there are weird problems caused by current throughput of entire network.

4. Try to eliminate unnecessary devices - if there is a possibility to connect computer directly to ADSL.

5. Use standard troubleshooting with nslookup and test, if ports are opened - with nmap (and similar).

6. Divide your trobleshooting into two steps - connectivity and name resolution.

7. Make sure that something like QoS does not play the role.

Rgds

Milos

• Proposed as answer by FangZhou ChenMicrosoft contingent staff, Moderator 9 hours 57 minutes ago

1. Network monitor will help you to resolve the problem. Wireshark will do the trick for you.

2. Double check the health or your router/ADSL. This problem need not be inside your computer. Other device(s) may help - another computer or mobile phone. Look into log file of router and ask ISP support for cooperation.

3. Sometimes there are weird problems caused by current throughput of entire network.

4. Try to eliminate unnecessary devices - if there is a possibility to connect computer directly to ADSL.

5. Use standard troubleshooting with nslookup and test, if ports are opened - with nmap (and similar).

6. Divide your trobleshooting into two steps - connectivity and name resolution.

7. Make sure that something like QoS does not play the role.

Rgds

Milos

• Proposed as answer by FangZhou ChenMicrosoft contingent staff, Moderator Monday, February 16, 2015 1:46 AM

Hello midource,

Do you mean that you will get the error about windows cannot communicate dns server after a while? And this issue will be temporarily solved after reset the router?

Please try the suggestion as Milos mentioned.
Please check if you can normally ping the DNS when you get the error message.

Please use the network monitor to capture the data and share it with us for analyzation.
http://www.microsoft.com/en-hk/download/details.aspx?id=4865
Upload to OneDrive: http://windows.microsoft.com/en-us/onedrive/add-photos-files
Share files: http://windows.microsoft.com/en-us/onedrive/share-file-folder

Best regards,
Fangzhou CHEN

Milos, 

Thank you very much for your help. I used another Router instead then the network is stability. So maybe the previous Router has a problem. Although network is stability now, but i'm still not sure the rootcause is the Router. So any way to check the Router if windows cannot communicate dns server?

Hello midource,

As the network is stability after your replacing the router, this issue is caused by the router.

What router do you use?
It is recommended to contact the manufacturer of the router.

Thanks for your understanding.

Best regards,
Fangzhou CHEN

Thanks all of you! Appreciate your help! The rootcause is Router! I think the problem is done.