Question DNS Server not responsing

Jul 23, 2019
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Moved into a new house with a new ISP on Fibre Internet in Australia made by Opticomm through HarbourISP.

Issue: Internet would randomly disconnect saying DNS server not available, stay offline until I reset router or logged into router settings on PC and basically restarted it from there.

Modem: Dasan- H640GR
Router: Netgear-D6400
Connections: 1 Windows 10 PC, 2 Phones on wifi and 1 Skystream III (Streaming Device, I think may be the issue. happens without it on though.)
DNS: Current settings are "Get automatically from ISP"
Primary : 8.8.8.8 (Google DNS)
Secondary: 1.1.1.1 (Previously had 8.8.4.4)
Netgear Image2
Netgear Image

What I've tried:
Update Router
Rang ISP around 10 phone calls, they're monitoring it.
Reset router numerous times
Numerous DNS servers and same result it works and then it doesn't work later on. (5-60mins)
Selecting IP address/DNS servers and reverting back to normal (Automatic from ISP)

Any other information please feel free to ask


PC Specs:

Windows 10 Pro 1607- OS build 14393.2214
Processor: Intel i7- 7700k 4.20ghz
Ram: 16GB HyperX Fury
System Type: 64bit

Thank you.
 
The DNS server not responding is very misleading it is like saying your tv does not turn on when the power is out.

Do you have any access to your "modem". I am not familiar with that device and it appears to be more than just a simple ONT. Mostly you want to look for any type of error message that says the internet is going down or has some kind of errors. Things like cable modem have logs that show problems.

Your goal is to see if the router is failing or if the internet is having problems. It could be the ONT or the ISP network in those cases. If it happens a lot maybe you could plug your pc directly into the modem. If that works the next step is normally to try a different router.
 
Jul 23, 2019
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I have access to Modem and Router however I myself am unfamiliar with Dasan and cant find much about it. I can only access Logs though routerlogin.net

"[Admin login] from source 192.168.0.2, Friday, Jul 26,2019 15:40:12
[DHCP IP: (192.168.0.3)] to MAC address 24:18:1D:07:31:18, Friday, Jul 26,2019 15:36:59
[Time synchronized with NTP server] Friday, Jul 26,2019 15:32:55
[Internet connected] IP address: 100.99.71.60, Friday, Jul 26,2019 15:32:54
[Initialized, firmware version: V1.0.0.88_1.0.88] Friday, Jul 26,2019 15:32:25
[Admin login] from source 192.168.0.2, Friday, Jul 26,2019 15:32:00
[DHCP IP: (192.168.0.3)] to MAC address 38:9D:92:6D:B0:CD, Friday, Jul 26,2019 10:32:16
[DHCP IP: (192.168.0.5)] to MAC address 30:07:4D:7A:62:C1, Friday, Sep 13,2019 22:05:22
[Internet connected] IP address: 100.99.77.89, Friday, Sep 13,2019 22:03:29
[DHCP IP: (192.168.0.4)] to MAC address 6C:21:A2:A5:C0:EE, Friday, Sep 13,2019 22:03:22
[DHCP IP: (192.168.0.2)] to MAC address 2C:4D:54:E5:A1:F5, Friday, Sep 13,2019 22:03:14
[Initialized, firmware version: V1.0.0.88_1.0.88] Friday, Sep 13,2019 22:03:03
"
 
That shows nothing abnormal. Mostly the device assigning IP addresses to end devices.

I would try to get into the device when it breaks if you can. Try ip 192.168.0.1 if the name does not work.

This appear you got in right after you booted the box so likely any error were deleted. Be nice if routers had some kind of storage they log to but they keep it all in ram.

To a point this is strange if this is the "modem". It would appear as if multiple devices are directly connected. The DHCP messages mean it is acting as a router.
 
Jul 23, 2019
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That shows nothing abnormal. Mostly the device assigning IP addresses to end devices.

I would try to get into the device when it breaks if you can. Try ip 192.168.0.1 if the name does not work.

This appear you got in right after you booted the box so likely any error were deleted. Be nice if routers had some kind of storage they log to but they keep it all in ram.

To a point this is strange if this is the "modem". It would appear as if multiple devices are directly connected. The DHCP messages mean it is acting as a router.
That would be the router, it's from routerlogin.net
 
I see, unfortunately the modem/ont hides stuff from you. In many cases you can actually unplug whatever cable/fiber goes into the modem and the router will think everything is fine. The ethernet port does not actually go down so it will happily send data to a dead modem. It takes a very long time for the router to figure out there is actually no internet connection, your pc will tell you much quicker.

My guess is what is happening is your internet is dropping and the ip address is changed when the connection comes backup. The router did not see the connection go down so it keeps the old ip. This may not be the case it is just a guess.

In any case the goal is to get the ISP to fix this. They will blame your router so you need to get ahead of them and test with a PC directly connected to the modem.

What you want to do run a tracert to some ip like 8.8.8.8. When you are directly connected the modem hop 1 should be the connection to the ISP...normally it is your router. You want to leave a constant ping run to this ip address and show them that it works and then all the sudden you lose packets.

If the problem does not occur when you are directly connected via the modem then you start to suspect the router is actually defective.
 
Jul 23, 2019
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Would having a static IP address this situation as well?
When I do ipconfig/all I get 192.168.0.1 as my DNS server well I get it for everything really,

I see, unfortunately the modem/ont hides stuff from you. In many cases you can actually unplug whatever cable/fiber goes into the modem and the router will think everything is fine. The ethernet port does not actually go down so it will happily send data to a dead modem. It takes a very long time for the router to figure out there is actually no internet connection, your pc will tell you much quicker.

My guess is what is happening is your internet is dropping and the ip address is changed when the connection comes backup. The router did not see the connection go down so it keeps the old ip. This may not be the case it is just a guess.

In any case the goal is to get the ISP to fix this. They will blame your router so you need to get ahead of them and test with a PC directly connected to the modem.

What you want to do run a tracert to some ip like 8.8.8.8. When you are directly connected the modem hop 1 should be the connection to the ISP...normally it is your router. You want to leave a constant ping run to this ip address and show them that it works and then all the sudden you lose packets.

If the problem does not occur when you are directly connected via the modem then you start to suspect the router is actually defective.
I'll give it a go when I am home, I did however manage to get home earlier and net was down so I checked logs again and here it is

I added gibberish to the Ip's and erased part of the MAC addresses.​

Code:
[DHCP IP: (192.168.0.ddsad)] to MAC address 6C:21:A2:A5:C0:, Sunday, Jul 28,2019 09:58:21
[DHCP IP: (192.168.0.dsa)] to MAC address 2C:4D:54:E5:A1:, Sunday, Jul 28,2019 09:54:45
[DHCP IP: (192.168.0.dsad)] to MAC address 30:07:4D:7A:62:, Sunday, Jul 28,2019 07:30:49
[DHCP IP: (192.168.0.dasd)] to MAC address 38:9D:92:6D:B0:, Saturday, Jul 27,2019 23:09:54
[Internet connected] IP address: 100.99.8.121, Saturday, Jul 27,2019 21:58:30
[DHCP IP: (192.168.0.dsa)] to MAC address 6C:21:A2:A5:C0:, Saturday, Jul 27,2019 21:58:20
[Initialized, firmware version: V1.0.0.88_1.0.88] Saturday, Jul 27,2019 21:58:04
[Initialized, firmware version: V1.0.0.88_1.0.88] Saturday, Jul 27,2019 21:55:51
[Time synchronized with NTP server] Saturday, Jul 27,2019 21:55:06
[Internet connected] IP address: 100.99.79.1dsad, Saturday, Jul 27,2019 21:55:06
[Admin login] from source 192.168.0.2, Saturday, Jul 27,2019 21:54:51
[DHCP IP: (192.168.0.dsa)] to MAC address 6C:21:A2:A5:C0:, Saturday, Jul 27,2019 21:54:51
[DHCP IP: (192.168.0.dsa)] to MAC address 2C:4D:54:E5:A1:, Saturday, Jul 27,2019 21:54:45
[Initialized, firmware version: V1.0.0.88_1.0.88] Saturday, Jul 27,2019 21:54:34
When I re-click my ethernet connection for details I get this

Code:
Network Connection Details

Connection-specific DNS Suffix:
Description: Intel(R) Ethernet Connection (5) I219-V
Physical Address: ‎2C-4D-54-E5-A1-
DHCP Enabled: Yes
IPv4 Address: 192.168.01
IPv4 Subnet Mask: 255.255.255.0
Lease Obtained: Sunday, July 28, 2019 10:47:05 AM
Lease Expires: Monday, July 29, 2019 10:47:04 AM
IPv4 Default Gateway: 192.168.0.1
IPv4 DHCP Server: 192.168.0.1
IPv4 DNS Server: 192.168.0.1
IPv4 WINS Server:
NetBIOS over Tcpip Enabled: No
Link-local IPv6 Address: fe80::e816:4db0:789d:8cb8%13
IPv6 Default Gateway:
IPv6 DNS Server:
Also in my "Network Adapters" in Device manager I have
Intel(R) Ethernet Connection (5) I219-V
Wan MiniPort IKEV2
Wan MiniPort IP
Wan MiniPort IPv6
Wan MiniPort L2TP
Wan MiniPort Network Monitor
Wan MiniPort PPOE
Wan MiniPort PPTP
Wan MiniPort SSTP
 
Last edited:
So without rereading this thread your problem could be the dns cache function in the router.

You do not need a static ip but you can change just the DNS option in your pc to use 8.8.8.8 as the DNS server directly.

There is a way to change it in the DHCP setting on most routers so it gives you 8.8.8.8 rather than giving you the routers ip. Be sure you are looking at the dhcp setting and not the wan settings if you change this.
 
Jul 23, 2019
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So without rereading this thread your problem could be the dns cache function in the router.

You do not need a static ip but you can change just the DNS option in your pc to use 8.8.8.8 as the DNS server directly.

There is a way to change it in the DHCP setting on most routers so it gives you 8.8.8.8 rather than giving you the routers ip. Be sure you are looking at the dhcp setting and not the wan settings if you change this.
I can change the dns on the router through its settings however same result, so you think change it on computers ipv4 setting only?
 
I always set mine in the end device but setting it some mobile devices is not simple at times.

If you get dns failures when you have the dns hard coded to 8.8.8.8 in your machine it almost has to be a internet outage. It is pretty much impossible for the google dns to go down, the 8.8.8.8 is actually duplicated on many machine all over the world so if one machine would fail it just moves to another.
 
Jul 23, 2019
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Thanks mate, I'll do that tomorrow. Hard to see what solution is because sometimes it'll stay up for few minutes,hours or day.
 

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