C6300 DNS issue

[porbus]

Modem-router worked perfectly for nine months, until I (unwisely, it turns out) decided to turn it off for a month when I went out of town. When I came back and turned it back on, I found the modem was still getting a signal from the ISP (all lights solid), and the computer (Mac) was still getting a signal from the router (both via ethernet cable and wifi), but the computer was unable to access the internet. Multiple reboots of all components, resetting modem -- nothing helped. Finally I discovered that running a ping test with an IP address was successful, but doing the same with a domain name failed. Hence likely a DNS issue in the modem. Any ideas, suggestions? (A different modem works fine with the same ISP and computer, so the problem is in the Netgear modem.)

[StephenB]

I'm moving this to the correct forum (it is not a ReadyNAS problem).

Your user manual is here: http://www.downloads.netgear.com/files/GDC/C6300/C6300_UM_17Nov2015.pdf

If you had enabled parental controls, begin by disabling them (page 26 of the manual).

You can configure the DNS server in the C6300 - (page 22 of the manual)  If getting the DNS server from your ISP fails, then you can try 8.8.8.8 (which is Google's public DNS server).

If you have difficulty changing these settings ,you can reset the C6300 and go through the setup again.

[porbus]

Thanks very much for the response. So far not much luck:

1. Parental controls were not enabled.

2. Following your suggestion, I looked at the DNS address configuration through Netgear Genie. It was set to "Get automatically from ISP." Since that wasn't working, I changed it to 8.8.8.8. Then I called my ISP to ask them to active this modem-router (I had been using a different modem). Still no internet.

3. I have reset the modem-router multiple times using a pin, holding it down for a full minute. No effect on the problem. I noticed a factory reset option in Netgear Genie -- might that be more effective than using a pin?

I am new to this, as you can probably tell by my posts, so the more detail you can provide, the more I will appreciate it. Thank you.

[StephenB]

Are you able to "ping" 8.8.8.8 from the mac?  http://www.macworld.co.uk/how-to/mac/how-test-ping-on-your-mac-3524076/

If so, that confirms that you have internet service, but the only problem is DNS.

If you can log into the C6300's web page, you can go onto the "advanced" home page, and you should see the internet port status there.

That will show you the public internet address that your ISP has assigned the router, and it will also show you the DNS addresses it is using.  Check that 8.8.8.8 is listed.

Also, check your Mac's settings to make sure it is actually using these DNS servers.  I'm not a mac owner, but there is a guide here that should work: http://www.macworld.com/article/2824564/slow-internet-edit-your-dns-settings.html

You might see 8.8.8.8 listed, or you might see the router's local LAN address (which should be 192.168.1.1).  It is also possible to manually set the Mac's DNS server to 8.8.8.8.  That's not the best approach, but it might be worth a test (if ping works).

[porbus]

Thank you, again, for this detailed post.

1. I can successfully ping 8.8.8.8 from the Mac. But when I ping "www.google.com," the ping fails.

2. I logged onto the C6300 webpage, following your suggestion, and set the DNS addresses to 8.8.8.8 and 8.8.4.4.

3. I checked on the Mac and determined that it is indeed using these DNS servers.

4. I rebooted C6300 and Mac both.

But I still can't get on the internet!

Below is some info that might be relevant from the Mac and the modem.

MAC INFO:

Ethernet is currently active and has the IP address 192.168.0.20.

C6300 INFO (from the internet port status window):

Account Name: C6300

Domain Name: (blank)

Internet IP Address: Get Dynamically from ISP (selected)

DNS Addresses: Use These DNS Servers (selected): 8.8.8.8, 8.8.4.4

Gateway MAC Address: Use Default Address (selected)

C6300 INFO (from the home screen):

Hardware Version	V3.0
Firmware Version	V2.01.14
Cable Modem Serial Number	3LM35B7Y06641
CM certificate	Installed
LAN Port
MAC Address	2c:30:33:6c:79:72
IP Address/Mask	192.168.0.1/24
DHCP	On

MAC Address	2c:30:33:6c:79:71
IP Address/Mask	184.152.168.198/21
Connection	DHCP Client
Default Gateway	184.152.168.1
Domain Name Server	8.8.8.8, 8.8.4.4

(I noticed that the MAC addresses given above are different from the MAC address indicated on the back of the modem itself, which is: 2c:30:33:6c:79:70. That's as it should be, I assume, but it caught my attention.)

Any ideas? Many thanks, again, for your help.

[StephenB]

Your setup looks correct to me.  

Maybe look again at the modem that works, and see what DNS server it is using (likely it is just automatically getting it from your ISP).

You might need to contact your ISP, and see if they are blocking it for some reason.

[porbus]

Thank you for your help and for the tutorial. I've tried using various DNS servers on the C6300 -- google's public ones and the ones used by on my other, working modem. No luck. Asked my ISP if they are blocking anything. They are not. A mystery. I will use my older, weaker, wifi-less but functioning modem for now. Thank you, again.

[StephenB]

---

@porbus wrote:

 A mystery. 

---

Yes.  I'm sorry we couldn't solve it.

The only thing we didn't try was to reinstall the firmware - if you have a chance, maybe do that.

[porbus]

Just to leave no stone unturned, I'm following your last suggestion and trying to reinstall the firmware. The only firmware to download for the C6300 that I find on Netgear's site is: Netgear Genie Installer 2.4.20. Is that correct? Following reinstallation instructions on this site:

http://kb.netgear.com/19841/Reinstall-the-firmware-on-a-router-without-the-setup-CD-recovery-tool?ci...

I've downloaded TFTP client software for Mac. In the C6300's LAN setup window, the LAN TCP/IP address is listed as: 192.168.0.1. I ping it and get replies. Now I open the TFTP client software, enter 192.168.0.1 in the address window and "password" in the password window. The file I attach is the NetGear Installer package (.pkg on Mac). Is that correct? Turning the C6300 off and back on, the power light immediately goes to solid green, without passing through an amber stage. I send the file while the C6300 is powering up. And get an error message! Have I done something wrong? Is there a better way to reinstall the firmware?

Many thanks, again, for your patience and help.

[StephenB]

You're right, Netgear has no firmware on the support site.  Probably best not to try the tftp method.