DNS on the NVG510

[colintheys]

Hello everyone,

     I just got uverse internet installed here and have had a problem since it was set up that has been stumping support for literally hours on end. The connection works quickly, but it is incomplete. Some random number of requests don't seem to go through. A page of images will be about 1/3 missing. Sometimes a page loads with no stylesheet. Sometimes a website is inaccessible. This has been true on three computers on the network and an ipod touch in multiple browsers and via both wifi and ethernet.

     I suspected it sounded like a DNS problem, so I locally set my computer to use google dns and the problem immediately vanished. The problem is that I can't seem to change the dns settings in the NVG510! I do have a netgear router that I could use, but I don't understand enough about such things to know if that would actually allow me to replace the dns. My quick test following the isntructions I found here for ip passthrough didn't produce any internet connection. I was wondering if anyone else has had similar problems or has any suggestions?

Thans,

-Colin

[lisfolks]

colintheys: is the NVG510 showing a valid set of DNS servers in the Broadband/Status tab? (There should be a Primary DNS and a Secondary DNS value, both with IP addresses showing.)

If so, have you tried putting those into your computer to see if they work? (I'm wondering here if the NVG510 is receiving the DNS values from upstream, but is not passing them down to your network.)

If those numbers don't work correctly, I wonder if AT&T support would be willing (and able) to define another set of DNS servers for your gateway. It may be that they're having problems with those specific servers, and they're not aware...

[colintheys]

Thanks! Really good idea. The router lists 68.94.156.1 and 68.94.157.1. When I entered those servers into my local machine, everything worked great. When I don't manually list those servers, the computer dns list just contains the ip address of the router. So it sounds like your first suggestion may be on target: that it's getting the dns from att but is unable to pass it down properly. Do you have any idea of what can be done about that?

Everything AT&T said on the phone indicates that they are unable to log in to acess the NVG510 remotely and that there's no way to change the dns servers on the device. But if it's a problem propagating somehow, then it sounds like I might have a chance at cracking it.

Thanks,

-Colin

[lisfolks]

I think the NVG510 has some firmware issues requiring an update or two to fix. Even if AT&T could remote into the NVG510, I doubt they could fix the situation in that case.

I can't think of any way to make the router propagate the DNS servers correctly off the top of my head. Since the issues you're seeing are random, I'm thinking it must be working some of the time at least. I'll think on it and post if I come up with a fix (other than manually entering the numbers into your computer, as you're doing now...) Hmm...

For kamickm, who is using an AEBS as a bridged router behind the NVG510, you might be able to enter the DNS values into the AEBS for your network. There are boxes for inputting the DNS values in the AEBS' IP address area (in Airport Utility go to Internet, then TCP/IP). Try putting the actual DNS IP addresses from the NVG510's status page into those boxes, restart the AEBS, and see if that helps!

[colintheys]

Do you think this is a case where I should ask for a new modem? Last time I was on the phone with them, they told me that I wasn't eligible for a new one becuase it "checked out" on their end. But if that might fix it, I could insist. I mean, I didn't configure any unusual settings at all and the problem is universal across every computer I've connected to the network.

Thanks,

-Colin

[lisfolks]

You could try asking for a new NVG510. Mine seems to be working fine, and I haven't manually configured any of the DNS info into my AEBS. What is your NVG510's software version (from the Device/System Information tab)? Mine is 9.0.6h0d48.

Kamickm, if you're checking this thread, please let us know what software version your NVG510 has as well...

[colintheys]

Yeah. Mine has the same software version number. I think I will ask for a new one, since there don't seem to be any settings I can change and I've seen the problem on every device anyone has connected to the network. I tried a factory reset. If they say they can't replace it again, I guess I'll just return it and go back to cable.

Thanks,

-Colin

[lisfolks]

Yeah, we'd switch, but our apartment complex doesn't have anything else (they use a 3rd-party satellite company to provide their cable, and it's going out all the time, so we don't use it either). So sad that AT&T, such a huge company, can't get it together customer-service-wise. I'm a T-Mobile customer, too, and I'm praying their purchase of T-Mobile doesn't go through and rapidly end what has been a wonderful customer service experience for us up until the announcement of their merger...

Good luck on your replacement quest!

[ajcherry]

Hi Colin-

Just wondering if you found a resolution to this issue, and if replacing your modem solved it.  I have the same problem, got a modem replacement, but it didn't seem to solve the issue, and I've talked to one other person who has had the same issue for whom a modem replacement didn't help either.  My modem is running 9.0.6h0d48, like yours was.  The replacement was running 9.0.6h0d34, but it ended up in a bricked state yesterday (perhaps it unsuccessfuly attempted to update itself to 9.0.6h0d48?) so I can't do further testing on it.  Fortunately, the old one still works as it did.

For me the problem is very reproducible when there is a load on the network (for example, while running a speed test or doing a download).  It seems even more sensitive to the upload bandwidth being saturated.

These modems are pretty new, so it wouldn't surprise me terribly if there were firmware bugs *or* hardware issues.  Though this issue just doesn't "smell" like hardware to me, because it doesn't seem to affect anything other than the DNS proxy on the modem.

-Andrew

[ajcherry]

lisfolks-

Do you happen to have a Linux or MacOS system on your network?  I've got a simple Perl script that can reliably reproduce the DNS problem on my network as long as I saturate my network bandwidth when running it (such as when doing a speed test).  I'd be really curious to see if you can reproduce it with your modem, given that you have the same modem software rev but you apparently aren't seeing the same problems.

I suppose it might work on Windows too if Perl is installed, but I haven't tested it on Windows.

-Andrew

[colintheys]

Hi ajcherry,

     I haven't gotten the unit replaced yet and haven't found any permanent solution. For now, I'm just setting the DNS on a per device level. It is interesting to know, though, that people who've gotten them replaced haven't had any success.

     My systems are all OSX. Interestinly, I don't need a load on the net work to reproduce the problem. It is 100% reliable and constant. It does seem to fluctuate in severity with time of day, though I haven't found any pattern. So at some times, there will be one image missing and at others, as much as half will be gone.

     Hearing that the problem didn't go away after an exchange, I might just return the thing now and go back to cable. For what it's worth lisfolks, I've actually found the uverse to be just as fast if not slightly faster than the cable offering in my location. So, if it weren't for the dns problem, I would stick with uverse over comcast in a heartbeat! Thanks for all the help!

-Colin

PS. If I do decide to pursue this with them further (I will at least give one more call), I will certainly post the results here.

[ajcherry]

Yeah, I don't really need a lot of load to reproduce the problem, just opening a web page with a lot of images is enough.  On the other hand, running namebench (a DNS benchmark utility) by itself, pointing it to the modem's DNS server, doesn't seem to trigger any issues.  That's what prompted me to try the perl script. I think it's the combination of some network load plus multiple simultaneous DNS queries that does it, which happens to be what will occur if you've got a multithreaded web browser loading a page with lots of inline content from multiple sources.

I've considered the possibility of switching to cable as well (which costs more in my area but has higher advertised speeds), but like you I've been reluctant to take the Comcast route, based on my past experience as a cable customer.  I was able to do a self-install for this service, which was a lot less trouble than arranging to be home for a tech to run new cable (definitely needed), etc, and pay the professional installation fee and reconnect fee.  If I wanted cable TV it would be a different story, but I'm happy to just use the cable wiring in the house for my antenna.  I've had some colleauges recommend Comcast Business Class, but I don't really want to budget that much for my Internet connectivity if I can avoid it.

I'm also not really all that convinced that I'd necessarily be better off with Comcast tech support if a similar problem were to crop up with their equipment.  I think it's probably much the same story with big support organization, and I think it has more to do with the dysfunctional way the typical IT support org is set up than anything else.  But that's just, like, my opinion. :-)

FWIW, several of my friends in the area that use Comcast have said that they use Google DNS anyway because of flakiness with Comcast's DNS servers.  YMMV.

[lisfolks]

I've already found at least one probable firmware issue with the NVG510 Residential Gateway (RG), ajcherry. I'm using the IP Passthrough functionality. According to its own instructions on the right-hand side of the tab, the RG is supposed to pass its public IP address through to another device, using its own DHCP - but it won't do it. I had to manually enter the information into my regular router (an Airport Extreme Base Station, aka AEBS) to use the Passthrough functionality.

I actually called Motorola to ask them questions about the NVG510 RG. They said, yes, that this is a new RG, and that it's designed specifically to AT&T's specification, not Motorola's usual setup. In researching my question, they were surprised to find that the NVG510 and the 2210-ATT1 RG, both AT&T U-verse-specific RGs, were designed without a true bridge mode. They said that was definitely not a usual Motorola thing.

As for my not experiencing the issues you and others are finding with the NVG510's DNS, maybe my use via the IP Passthrough is allowing the DNS to work as it should. Again, I didn't manually enter the DNS settings into my AEBS - I just have the NVG510's IP address in the DNS textbox as automatically passed by the NVG510. However, maybe using the IP Passthrough functionality is bypassing or unblocking something that's blocked occasionally with high-load pages... Hmm...

In my case, I already had the AEBS with all the settings I needed. The NVG510 is very basic in some ways, and can't do some of the things I wanted to do (use fixed IP addresses, for example, via DHCP). The first method I used to "bridge" the NVG510 left everything locking up once there was a load on my network, so maybe that was because of the DNS problem. However, when I realized how to set up the IP Passthrough, that worked magnificently, and has continued to do so overall. Here's a link to my IP Passthrough "bridge" solution for the NVG510 with an AEBS. I would expect that a router-knowledgeable person could translate the AEBS instructions to the router of their choice:

http://forums.att.com/t5/Features-and-How-To/NVG510-Bridge-Mode/m-p/2928989#M29846

Oh, and obviously, this isn't going to help those who don't have (or need) a 2nd router on their network. For people with only a NVG510, I would recommend entering the DNS values manually on each of their computers, as Colin described in early posts on this thread. For people who have a 2nd router, but have put that router into bridge mode, I would recommend manually entering the DNS values into their bridged router to see if it helps.

[ajcherry]

lisfolks-

I'm using IP passthrough too (using a Cisco/Linksys E2000 running dd-wrt), but my E2000 *is* getting the public IP address.  Here's what I did to set it up:

1. Configure the modem on a different subnet than the rest of my LAN.  My LAN was on 192.168.1.x, so I either had to change the modem or the LAN.  Since I didn't want to re-IP my entire network, I configured the modem to 192.168.0.1 instead, and changed its DHCP pool to be on 192.168.0.x. 

2.  I reduced the DHCP range on the Motorola to a single IP address, just to make sure I always knew what private IP my E2000 would end up with if it didn't get the public IP.  But in retrospect this ended up being unnecessary, since it eventually ends up with the public IP, and the E2000's configured LAN address (on 192.168.1.x) is used to access its GUI.

3. I use the following passthrough settings:

Allocation Mode: Passthrough

Default Server Internal Address: <empty>

Passthrough Mode: DHCPS-fixed

Passthrough Fixed MAC Address: <WAN mac address of my E2000>

4. I turned off all of the firewall settings I could on the Motorola.  I don't need two firewalls.

One thing to note is that my E2000 (and probably any other wireless router, for that matter) has three distinct MAC addresses: one for the LAN interface, one for the WAN, and one for wireless.  I used the WAN mac address, since that's the interface that the Motorola is connected to.  I suspect that this would not work if I'd inadvertently used one of the others.

Another thing to note is that if the modem doesn't currently have an established connection to the internet, it will hand out a local address from the DHCP pool with a very short lease (10 minutes).  After another renewal will hand out the public IP with a longer lease.  I do notice that it ends up handing out an odd netmask (255.255.255.255), but I haven't seen any ill effects.

Just FYI, there's a draft version of the modem's admin manual on the FCC's web page, among the supporting documentation for its FCC certification.  Basically you just need to look up the FCC ID (which written on the side of the modem, normally hidden by the base).  I posted the details here:

http://www.dslreports.com/forum/r26570998-Motorola-NVG510-owners-any-DNS-problems-

[ajcherry]

I just realized the above post might be a bit confusing because I used WAN in two different contexts, so I just edited the post to hopefully make it clearer, and correct some errors I realized I made.

-Andrew

[lisfolks]

"I'm using IP passthrough too (using a Cisco/Linksys E2000 running dd-wrt), but my E2000 *is* getting the public IP address."

Thanks for this info, ajcherry. Interesting! Which port of your E2000 do you have the NVG510 plugged into - the WAN or one of the regular LAN ports?

Also, a side note: I talked to AT&T support last night for another issue, and they acknowledged there are known firmware issues, including this DNS-passing issue and an IP Diagnostics issue, with the NVG510. A firmware update is currently scheduled to be installed automatically sometime late this month (December 2011).

[troyamiller]

"A firmware update is currently scheduled to be installed automatically sometime late this month (December 2011)." ...

...I hope so. This modem has been a constant headache for me. I recently switched from AT&T DSL to AT&T U-verse. I too have run into the DNS issue - and the easiest solution for me also was to just enter Google DNS on a machine by machine basis. That has seemed to resolve that problem...

...but my bigger problem is that port 1723 on this thing WILL NOT OPEN. I work remotely from home much of the time, via VPN connection to my office. And now I can't. This issue also seems to be pretty well documented in the forums - and hopefully this promised firmware update will 1) actually come out; and 2) solve that problem as well. Not holding my breath...

[lisfolks]

troyamiller, when you say that "port 1723 on this thing WILL NOT OPEN", what have you tried?

On the Firewall tab, then NAT/Gaming link, there is a dropdown where you can select PPTP as an Application Hosting Entry. This is SUPPOSED to open port 1723 and forward it to whatever device you select in the Needed by Device dropdown.

Now, you do need to click the Add button once you make the selections. Then, you should go ahead and restart the NVG510 (Device tab, then Restart Device link, and follow the instructions on that page) in order to activate the change.

Does that not work for you?

[troyamiller]

Thanks for the reply... but no (familiar territory to me). That was the first thing I tried - both adding the PPTP connection, as well as simply directly adding port 1723 as a 'custom' app. DID restart the device (on both occasions)... and no luck.

However, you mention (after device restart) "follow the instructions on that page"... guess I didn't see anything there (tho I was admittedly not reading closely)... I will check that out and report back...!

[lisfolks]

troyamiller said "However, you mention (after device restart) "follow the instructions on that page"... guess I didn't see anything there (tho I was admittedly not reading closely)..."

There's nothing special on that page. I just wanted to make sure you had done a complete restart - which it looks like you did.

I also did see that other people had tried the PPTP service setting without success - yeah, probably another firmware issue.

Only a couple weeks left in this month. I'm looking forward to that update... (I think...)

[troyamiller]

Now, only a couple of DAYS left in this month.  Pretty frustrated with this thing.  Anyone hear any new news of a firmware update on the horizon?

[lisfolks]

No sign so far on mine...

[tcaradonna]

Where would they post a firmware update?  Or does it happen automatically. 

An ATT tech told me a couple weeks ago there would be a new one coming out December 2011, which has now all but passed.  My box is still running 9.0.6h0d48

Fortunately my network is still working, (now going on 3 weeks) but I have a feeling that isn't going to last with the way the passthru & DNS has been jerry-rigged on all our systems now.

[troyamiller]

Hmm.  January 1 and nothing.  Nice to see that they got right on that.  The IP passthru ridiculousness works only sporadically on mine... and now, I am officially into my busiest time of year (I write some niche tax software applications).  This is my livelihood, and not being able to VPN into my office at night is and will continue to be affecting my productivity.  Perhaps I should start billing AT&T for MY time lost... (frustrated).

[lisfolks]

Yep, officially out of December without an update.

Per the AT&T rep, the firmware update should be applied to the NVG510 automatically via their system; there is nothing we need to do from our end.

Maybe they're taking extra time to get that VPN issue fixed... okay, New Year's optimism there - plus some hope that the extreme emotions that blocked their T-Mobile merger maybe opened their eyes that their customers are (just a little) PO'd???

[donkdonk]

I just wanted to join in on this thread to confirm let AT&T know (if they watch this forum) that I've got the same DNS issue with U-Verse & the the NVG510 router.   It's completely frustrating.  Hardcoding DNS servers (I use google's) does address the issue, but its a pain in the butt (esp. for mobile devices) and just something we shouldn't have to deal with.

[troyamiller]

Not sure why I bothered to get my hopes up... ANOTHER month gone with NO UPDATE.  This is very, VERY frustrating - and it CAN'T BE THAT DIFFICULT.

[AnathemaTic]

In response to hard coding the google servers, depending on your location they might be quite a bit longer round trip than using att's. ATT DNS servers are 68.94.156.1 68.94.157.1, the issue isnt with their servers, its the NVG510. Really your best bet is to use a seperate router with the NVG510 in passthrough. If you use a seperate router you have a lot more flexibility and dont have the hard code the devices, you can set the router's dhcp function to do it all for you. Try pfsense for firewall/router, www.pfsense.org.

For what its worth, heres my DNS resolve times, ATT DNS is about twice as fast as google or OpenDNS

--------ATT--------------------

C:\>ns_bench.exe 68.94.157.1 68.94.156.1
Nameserver              Response Time (ms)
                        min/avg/max/stdev/retries
68.94.157.1             14.00/15.00/16.00/0.89/0
68.94.156.1             14.00/14.20/15.00/0.40/0

--------Google--------------------

C:\>ns_bench.exe 8.8.8.8 8.8.4.4
Nameserver              Response Time (ms)
                        min/avg/max/stdev/retries
8.8.8.8                 31.00/32.00/33.00/0.63/0
8.8.4.4                 31.00/32.60/35.00/1.36/0

--------OpenDNS--------------------
C:\>ns_bench.exe 208.67.222.222 208.67.220.220
Nameserver              Response Time (ms)
                        min/avg/max/stdev/retries
208.67.222.222          46.00/48.80/52.00/2.04/0
208.67.220.220          42.00/46.80/55.00/5.23/0

ns_bench only tests google.com, you can also use the GRC DNS benchmark http://www.grc.com/files/DNSBench.exe

[troyamiller]

Mid-April now and still no update. This is ridiculous.

[lisfolks]

May 1st, and still no update. Okay, 5 months late so far.

Additionally, I just finished answering some Apple users' questions. AT&T is telling them that this is completely an Apple issue. Now how's that for trying to ensure you only have to support one operating system. I'm pretty sure that at least some of the people responding to this thread are NOT Apple users. Hmm...