DNS server not foud error repeats on Ethernet port only

DNS server not foud error repeats on Ethernet port only
DNS server not foud error repeats on Ethernet port only
2020-10-27 22:24:13
Model: Archer A7
Hardware Version: V5
Firmware Version: 1.0.15 Build20200721

This annoying error randomly occurs repeatedly, requiring reset of the router to resolve.

When I by pass the router and connect the RJ45 cable directly to DOCSIS3.1 modem port directly. It connects to Internet. So it proves the fault is within the router, not the ISP nor my PC port.

In the meantime, all other Ethernet ports seem to work fine, and WiFi connections also work fine. This IS Wierd and quite disappointing error.

Please HELP me resolve it permanently, plase.

 

My PC (AMD chip sets) OS is Win10 up to date.

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#1
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10 Replies
Re:DNS server not foud error repeats on Ethernet port only
2020-10-28 18:16:00
Have you tried a different Ethernet cable?
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#2
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Re:DNS server not foud error repeats on Ethernet port only
2020-10-28 18:58:46

@ArcherC8 

First, thanks for your respond!

Yes, I have. Please note that the same cable connected drectly to DOCSIS3 broadband Modem accessing Internet fine, which is another test and proof.

Now when it seems to stablize awhile, all of a sudden my laptop connected via WiFi fails to get connected access Internet, while connected to AP.

Have rebooted the laptop to no avail. When I reboot the A7 router, both unit connections work, again for several hours or even days, then the same/similar failures occur.

These two itermittent failures are very mystifying.

Other devices wired like Brother printer, TiVo, stay connected, as well as other WiFi devices like Galaxy cellphones, Kindle Fires, Fire TV, Apple TV, etc.

Is mine an exception or have there been more failures, I wonder.

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Re:DNS server not foud error repeats on Ethernet port only
2020-10-28 23:11:08

 

try2bwise wrote

@ArcherC8 

 

all of a sudden my laptop connected via WiFi fails to get connected access Internet, while connected to AP.

Have rebooted the laptop to no avail. When I reboot the A7 router, both unit connections work, again for several hours or even days,

@try2bwise 

 

The subject is Ethernet port only?

 

Now you brought in an AP and Wifi?

 

Before you said the cable was good as you connected it straight to the modem?

 

What exactly is your setup/topography?

 

Do you have 2 routers, one an AP plugged into the first router via Ethernet cable? That is what it sounds like? C7 in AP mode connected to another router. Reboot the C7 and you work again.

 

If so, what is ahead of the C7? Can you plug it into another port on the router ahead of it?

 

If I am correct, when it fails, can you log into the C7? Do you see on the Internet page a WAN IP Address or is it just DNS IP Address that is missing?

 

If I read this all wrong, I appologize and will go back to lurking.

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Re:DNS server not foud error repeats on Ethernet port only
2020-11-16 01:15:25

@IrvSp 

 

First: thanks again for staying on this and responding!

 

Let me summarize again as simply as shown in the attached file of screen print.

I have only one AC1750 as the router, there is no other AP or repeater behind.

It is fronted to a (Motorola) Arris cable modem (to Suddenlink).

Main issue is limited to the Ethernet port to one desktop PC.

All other connections to other devices, including printer, etc. (and many are via WiFi) are fine.

That WiFi event on laptop seems to be an exception, which has not recurred since.

 

Note that I have even tired with secondary DNS servers with 8.8.8.8, 8.8.4.4 to no avail.

Any clue or suggestions?

Again, thanks for staying engaged and trying to help!!

 

File:
AC1750 net map.docxDownload
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Re:DNS server not foud error repeats on Ethernet port only
2020-11-16 12:04:06

@try2bwise

 

Have you tried swapping Ethernet ports on the router with a known working port? Still, I can't think of a port stopping Internet but still allowing LAN use?

 

Could the PC be using an IP Address that isn't on the LAN? IPCONFIG /ALL could determine that (I assume you are using Windows)? Either GATEWAY is wrong or the IP Address that the device is asking for.

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#6
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Re:DNS server not foud error repeats on Ethernet port only
2020-11-16 12:06:52
Since everything is working except one PC, then one would assume that the most logical is an issue with the PC or the cable going to the router. To be sure it is not the router, power down the router, switch Ethernet ports with another device, and power it back up, this will ensure that you do not have a bad port on the router. Next would be to verify the cable, which you have done previously bt connecting to the modem. When connected to the modem did you happen to check the speed. If your ISP speed is greater than 100, did you get that speed? for example, If you have 200 service and got only 100 when connected to the modem then you may have a bad cable or PC setting. So that leaves the PC. It appears you have a Windows PC so I will let other more knowledgeable posters help with that. I switched to Apple and have not looked back.
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Re:DNS server not foud error repeats on Ethernet port only
2020-11-18 15:55:13

@ArcherC8 

First, Thanks for your continued interest and dialogue!

All physical components seem to be proven fine as have been tested including materially swapped.

Attached below is a speedtest meeting the spec of 100/8 mbps down/up link services by my ISP, Suddenlink cable service; not the best but monopoly, so the only viable option.

One recent surprise, pleasant I might add, is the storm of repetitive errors, almost once every 24-48 hrs. has been reduced to no recurrence of error so far over 3 days.

I keep my fingers crossed. So one would ask, what changed if any?

One: the latest firmware update on AC1750, supposely minor and the tech notes state nothing of correcting this error, only referring to some business servers related.

So, coincidence, perhaps? But I am not complaining, but rather holding my breath to see when the next incident will occur. Stay tuned, please.

Thanks again!!

 

File:
Speedtest results.pdfDownload
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#8
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Re:DNS server not found error repeats on an Ethernet port only
2020-11-23 17:15:18

@try2bwise 

Well the gremlin seemed to revive after being dorment for around a week or so.

Though I can tolerate and live with this situ, I wondered about two potential contributing factors:

1. I wonder if i should try this PC MAC to a static, other than 192.168.0.179 assigned via DHCP; though it shouldn't make difference, but curious.

2. Also shouldn't matter, I wonder if I should enable IGMP snooping and proxy since I have IPTV traffic with STB with TiVo, FireTV, AppleTV, etc.

    And if so, V2 or V3?

Trying to figure this out and hope to resolve permanently, I wish.

Grunting...

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#9
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Re:DNS server not found error repeats on an Ethernet port only
2020-12-05 22:03:28

I have tried all sorts to resolve this mysterious failure, including actually make this PC Ethernet port be a static IP with renewal time increased to 1440.

And disabled IPv6. It seemed to improve/reduced the failure rate, but now still fails with a different msg than "DNS server not found."

Now the error message is "broadband modem or its connection to the router failed," which is untrue because all other WiFi connect devices have Internet access fine and healthy. And its Ethernet connection to the router is up and working, except that its Internet connect is down. Really strange going on.

Any clues or suggestions? Am I the only one dealing with this network gremlin?

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#10
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Re:DNS server not foud error repeats on Ethernet port only
3 weeks ago

I am pleased to report that this problem has been resolved, as the problem has not recurred for 3 weeks.

I have found a later version of Driver version 10.24.1208.2017

for Realtek PCIe GBE Family Controller.

MS Windows 10 didn't find it, I had to research the manufacturer web site for it.

Lessons learned, apparently is: do NOT just trust MSW will find the best/latest Device Driver. When in doubt, DIY.

Moderator, please close this thread.

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#11
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