× Introducing the Orbi 970 Series Mesh System with WiFi 7 technology. For more information visit the NETGEAR Press Room.
Orbi WiFi 7 RBE973
Reply

WNR2000v4 keeps changing internal ip address

Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

If the files are not too large for you to e-mail, then you are welcome to send them to me at ataylor@netgear.com

Message 26 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

I would like to e-mail them to you, however, they are about 100Mb. This will not be accepted by any free mail companies like google, MS, etc. I have some sort of file server running for my website, you can download them from there? I will sent you a e-mail with links to the files from the server.

Message 27 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

That's fine, I'm in the UK and it's getting late here now, so will download tomorrow.

 

Correction - downloading now, will check tomorrow.

Message 28 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

I hope you have slept well. Anyway, I started the modem test. It seems it is a very busy signal. A lot of ARP requests from different IP's. I also have a new IP address so I need to change some things.

 

When I hooked up the modem with my computer I noticed that I got an 192.168.1.10 address, normally this is not so because of the router. When I executed the ifconfig (yes, it is correct. I work with Linux (ifconfig) instead of Windows (ipconfig)) command again I got the new 94.213.*.* IP address. This made me wonder why this is not happened before. I had never this problem for months.

 

I will run the modem test with Wireshark to be sure. I will contact you again by e-mail if the logs are done. I will let it run for 24 hours like the router test. Since I'm connected directly I cannot change the router but I will when it is done.

Message 29 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

OK, that’s fine.

 

Just to be clear, was that last capture with the router between the modem and the computer? I saw a lot of 192.168.1.x IP addresses in there.

Message 30 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Yes, that was with the router connected. Now I'm doing a test with out the router, so my computer is directly connected to the modem.

 

It is generating a lot of traffic. Lots of TCP requests... I think the next file will be huge. Is this a problem? I'm affraid that it will be to big to download. I almost have a half of a million entries in the log already. The router didn't get that much i think.

 

Offtopic: You may have a bug in your forum software. In the notifications (top right) it is stated that you and Kenneth are replying to my topic. But Kenneth has answered once.

Message 31 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

If you take a look at the captured data you might find that you can filter out large chunks so that it doesn’t get recorded, in fact for the purpose of this investigation you could set a filter to only capture data where the source is 192.168.1.x

 

I see that also with notifications, I’m not sure if that’s the way it’s meant to work or not.

Message 32 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

The only address I have seen so far is this one:

 

549898    42352.201591000    94.213.*.*    192.168.1.18    TCP    74    [TCP Retransmission] 46251 > http [SYN] Seq=0 Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=10691264 TSecr=0 WS=128

 

It is not the source but the destination. It seems like that the external IP is trying to sent something to an internal IP address. So, looking at my IP configuration at my computer, I can only conclude that it does not exists.

 

Offtopic: I don't think it is meant to be used this way because when I looked at it, it was 34 minutes ago. Now it is 8 hours ago and Kenneth responded earlier in this topic and only once.

 

 
Babylon5 and KennethL replied to the topic WNR2000v4 keeps changing internal ip address 8 hours ago. 
 
So to me it looks like two people had a look and replied to my answer, which you only did.
Message 33 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

Where there several of those messages or just one? For a complete TCP transaction I would expect some response if it’s a legitimate message.

 

I suppose one last thing you could do if you have not done so already is to capture traffic between the modem and the PC when the modem boots up.

 

I will pass your comments on to Kenneth.

Message 34 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

No, I got only those, there is "never" an answer to it. Kinda like a one-way street so to speak.

 

When I switched the computer from the router to the modem it did not connect. I had to reset de modem by pulling the power. After that I directly took a look at the IP configuration which outputed an internal IP address of 192.168.1.10. This is not my static address I normally use. When I looked again I got the external address of 94.213.*.*. So this made me wonder is there is some internal routing capability within the modem and uses the 192.1681.1 range to establish a connection before you are connected.

 

As I see it now, the modem requests an IP address from my ISP and when received it will route/give the signal to my netgear router. When it does use an internal routing procedure in the range 192.168, then that might be the problem. However, I'm wondering how the modem can "leak" the 192.168. range to the router.

Message 35 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

I think I have it. It was as before, I needed to reset the router because I had no connection. I had Wireshark running on the router or to watch the router and it changed it's IP address to 10.0.0.0 range. I have the logs if you want to take a look at them, this file I can e-mail to you. It is small enough.

Message 36 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

What will commonly happen with a DOCSIS modem is that before a connection is established with the ISP equipment, the modem may temporarily allocate a 192.168.100.x IP address, and it may also do this if the connection to the ISP fails, this allows for easy communication / diagnostics with the modem.

 

I suspect that you modem may well be allocating a 192.168.1.x IP address during startup, to be replaced by your public IP shortly afterwards.

 

With many cable modems, it is necessary to reboot the modem when the connected equipment changes, or the connected MAC address changes.

 

So I would expect that the Netgear router will change its LAN subnet during the period that the modem reboots, does this match with your observations?

Message 37 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

It does now. I do not know if the modem is using DOCSIS, I know the routers are like cisco and some others but not the modems.

 

I would like to confirm this, so I will contact my ISP again for information. After that I will report back.

 

Thanks Andy

Message 38 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

I'm waiting for a respons of the ISP community but according to the helpdesk of my ISP the modem has an internal routing function to let the main signal thru. However, they do not know which address this is because it is automaticly generated.

 

I will change my internal IP to another range so this can not happen again.

 

Since I do not like any survey thingies I will give my feedback here.

 

Andy, thank you for helping me and I have learned a lot. As for service from Netgear, it is great! Keep it up 🙂

Message 39 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

Well thanks very much for that.

 

If you do find out any more information about the modem I would be interested, but I think your idea of changing the router LAN subnet to avoid the issue un future is sound.

 

Regards,

 

Andy

Message 40 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address

Hi Andy,

 

I have some more information on this subject from my ISP community. It is a rough translation with google translate, I hope you understand it.

 

This seemingly "strange phenomenon" can be explained. What I can say at this stage is that both parties have no guilt here. This phenomenon stems from two requirements that a manufacturer must meet when NAT is used with the product. See https://tools.ietf.org/html/rfc4787#section-4.4 for details.

Why you can see this at a modem reset is because the RF interface of the modem is not connected yet to the CMTS. As a result, the DHCP server of the modem itself is active until there is a connection to the CMTS. The WAN interface of your router detects a link down / up event and then try again to obtain an IP address. The WAN interface from your router will then receive a private IP from the modem of the same sequence which is then used your router at that time. The modem does not know that your router uses internally the same private IP range. This clearly presents a problem and configure your router responds correctly by itself with another private IP range. Why is the DHCP server of the modem active when there is no connection to the CMTS? Because you still can logon to the management interface of the modem.

Manufacturers must implement one of the following two things to make it work.

All traffic between internal / exterene clients correct translation and forwarding. This is difficult because you need a solution such as Session Traversal Utilities for NAT server. If the two clients are the same ISP who does double NAT, you are also dependent on the correct NAT hairpinning implementation of the ISP router.

The second solution is automatically ensure that the internal and external IP ranges do not overlap / are identical.

Manufacturers logically opt for the second easy solution. How can you solve this problem permanently? If your local network eg. 192.168.0.0 Class C network can be used eg. Set your router to use IP network 192.168.1.0.

Message 41 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

Yes, that’s pretty much how I understand it to work. For me it’s very rare for the ISP connection to fail, but on those rare occasions in the past before I had an intervening router I would find that the attached PC would have a 192.168.100.x IP address which allowed me to access the modem and see what the issue was. Since getting a router I have always operated my LAN with a subnet of 192.168.12.x and this has never caused any issues even with several changes of modem model.
Message 42 of 44
Anonymous_fan
Aspirant

Re: WNR2000v4 keeps changing internal ip address


@Babylon5 wrote:
Yes, that’s pretty much how I understand it to work. For me it’s very rare for the ISP connection to fail, but on those rare occasions in the past before I had an intervening router I would find that the attached PC would have a 192.168.100.x IP address which allowed me to access the modem and see what the issue was. Since getting a router I have always operated my LAN with a subnet of 192.168.12.x and this has never caused any issues even with several changes of modem model.

I didn't know this. For me it is a first. Although I have to say that I had never problems with a modem before. A router is another story though.

 

Anyway, thank you! The last thing to do for me is to mark an answer to be the solution. But which one? I assume the best one is the one which help others too. Any ideas on that?

Message 43 of 44
Babylon5
NETGEAR Employee Retired

Re: WNR2000v4 keeps changing internal ip address

I would suggest your post 41.
Message 44 of 44
Top Contributors
Discussion stats
  • 43 replies
  • 17090 views
  • 0 kudos
  • 3 in conversation
Announcements

Orbi WiFi 7