Default gateway going blank intermittently

By cAnon
in Smart Home, Network & Security

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cAnon

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Every once in a while my computer will lose the default gateway (blank, not 0,0,0,0) but releasing and renewing seems to fix it reliably every time it happens. I just can't seem to figure out the root cause of it. I'm using dhcp to acquire my settings. I'm not a complete novice but I'm also not a CISCO pro. Any help would be appreciated.

Grand Master

+BudMan MVC

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  • MVC
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so your saying it loses just the gateway?  Or it changes from the IP it should have say 192.168.A.X with gateway 192.168.A.Y to say an IP that starts with 169.254.x.x ?

 

If your saying it still shows its 192.168.A.X address but the gateway is blank - than that would be weird!!  Can you post the output of your ipconfig /all when its working and then when you have this gateway issue.  My guess is your dhcp lease is just expiring and you end up with a APIPA or 169.254 address until you force a renewal/get of dhcp address again.

 

You can see here the lease info, when I got it, how long its for - who the dhcp server was, etc.

dhcpleaseinfo.thumb.png.c021ae5f27e05070b19172466c0aef94.png

 

So you posting this info when your good, and then when you have your problem - before you fix would be very helpful in determining your problem

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cAnon

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Hi all! I can't post a screenshot of it working but I'll put one up of what it's at now. I haven't tried setting a static address as I've never had a problem with it till now. I've flushed dns, released and renewed my address a few times which fixed it temporarily but now I get and error when renewing an address. Also I've got Win10 Pro version 1703 build: 15063.413 7f2401d4aa9612ed30ae7740321dab5a.png

 

I've got a garbage built-in wireless receiver connected to a POS router which is connected to a modem. I've had dns troubles in the past but I reset my router a few times and they haven't returned.

Grand Master

+BudMan MVC

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  • MVC
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It has ZERO to do with your gateway being gone - look you do not have an IP, you have APIPA (Automatic Private IP Addressing)  169.254.x.x --> Its a link local, no its not going to have a gateway.

 

You have a problem with your dhcp server.. Windows will give itself this address when set to be dhcp, and the dhcp server does not answer.

 

 

 

 

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cAnon

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It has ZERO to do with your gateway being gone - look you do not have an IP, you have APIPA (Automatic Private IP Addressing)  169.254.x.x --> Its a link local, no its not going to have a gateway.
 
You have a problem with your dhcp server.. Windows will give itself this address when set to be dhcp, and the dhcp server does not answer.
 
 
 
 

Alright..so how do I identify the problem with my dhcp server? Or will creating a static ip fix it?
Grand Master

+BudMan MVC

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  • MVC
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Well for starters what is your dhcp server?  I assume your router - what router is this? Make and model, what firmware is it running?

 

Do any other devices have issues with dhcp when your having issues, you state release renew currently not working, etc.  So no devices on your network are able to get an IP?  Points to dhcp server being down.. If just this 1 client and all other devices working then points more to problem with device itself and not the dhcp server.

 

A simple sniff on the device will help  you determine if the dhcp server is answering or not..

 

Dchp is pretty basic to troubleshoot.  I am going to take a guess that its not something you could do (no offense) or you wouldn't be here in the first place.

dhcp.thumb.png.402d30705248a1ca89113dbccbd2701e.png

 

I would suggest you just reboot your router to see if that fixes it.  Or restart its dhcp server.  But if you can manage to download wireshark and get a sniff and then post it we can run through troubleshooting dhcp for you..  See above is typical discover process with offer, request and then ack of a client getting a lease from a dhcp server.

 

If creating a static doesn't get your client online - then points to something else going on with your network that is preventing dhcp from working, like just no connectivity at all.  But setting static would be just a step troubleshooting not really a fix of the root cause to your problem.

 

This seems to be limited to wifi - maybe your wifi is not working at all, even if shows connected.  Have you rebooted the wifi router?

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cAnon

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Well for starters what is your dhcp server?  I assume your router - what router is this? Make and model, what firmware is it running?
 
Do any other devices have issues with dhcp when your having issues, you state release renew currently not working, etc.  So no devices on your network are able to get an IP?  Points to dhcp server being down.. If just this 1 client and all other devices working then points more to problem with device itself and not the dhcp server.
 
A simple sniff on the device will help  you determine if the dhcp server is answering or not..
 
Dchp is pretty basic to troubleshoot.  I am going to take a guess that its not something you could do (no offense) or you wouldn't be here in the first place.
dhcp.thumb.png.402d30705248a1ca89113dbccbd2701e.png
 
I would suggest you just reboot your router to see if that fixes it.  Or restart its dhcp server.  But if you can manage to download wireshark and get a sniff and then post it we can run through troubleshooting dhcp for you..  See above is typical discover process with offer, request and then ack of a client getting a lease from a dhcp server.
 
If creating a static doesn't get your client online - then points to something else going on with your network that is preventing dhcp from working, like just no connectivity at all.  But setting static would be just a step troubleshooting not really a fix of the root cause to your problem.
 
This seems to be limited to wifi - maybe your wifi is not working at all, even if shows connected.  Have you rebooted the wifi router?


This computer is the only one having trouble connecting. Every other device has internet (phones, laptops, tablets). I'll get a sniff from the trouble PC and get back to you.
Grand Master

+BudMan MVC

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  • MVC
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Does it work if you plug it in with a wire?  It shows you connected to wifi?

 

But yeah a sniff will be most helpful in showing if your seeing any other traffic, ie broadcast from other devices on the network which would show that connectivity is working.. And then should see your discover go out when you do the renew, etc.

Grand Master

+BudMan MVC

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  • MVC
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Personally I would disable tunnel adapter, unless its the only way you can get ipv6 and you want IPv6.. It can be a security issue since your tunneling ipv6 traffic through ipv4 and your router firewall would not block that, etc.  Looks like you have ipv6 disabled on your actual interface.. So you want the teredo working?

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cAnon

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Personally I would disable tunnel adapter, unless its the only way you can get ipv6 and you want IPv6.. It can be a security issue since your tunneling ipv6 traffic through ipv4 and your router firewall would not block that, etc.  Looks like you have ipv6 disabled on your actual interface.. So you want the teredo working?


I would like IPv6 to disappear entirely. I'm not sure how to disable the tunnel adapter. It seems to only appear when I have a working connection though.
Grand Master

+BudMan MVC

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  • MVC
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well yeah its only going to be able to get a tunnel address when it can tunnel through a working ipv4..

 

To disable ipv6 completely you can do from cmd prompt (elevated to admin)

reg add hklm\system\currentcontrolset\services\tcpip6\parameters /v DisabledComponents /t REG_DWORD /d 255

 

Reboot.. To put it back like it was out of the box then

reg delete hklm\system\currentcontrolset\services\tcpip6\parameters\ /v DisabledComponents /f

 

Reboot

 

To just delete the teredo you should be able to do from netsh command via admin cmd prompt

netsh interface teredo set state disable

 

edit: if all you want is dhcp then you could filter on udp port 67.

 

edit2:  As you can see I normally just have all ipv6 disabled - but clickity clickity I can have it back with full ipv6 access.

ipv6.thumb.png.8ba01fba6a9195721d692eff7a51978d.png

Grand Master

+BudMan MVC

Posted
  • MVC
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none of that is dhcp..  You seem to be talking to steam though..

 

Capture filter would be a simple udp port 67 filter..  Here is screenshot

 

capturefilter.thumb.png.4f00c38c474424a65457f0e6a0af6db7.png

 

If you don't filter it and your working with valve for example that is using udp, than there is going to be way too much noise to make it easy to work with.  Also your prob going to want to save that file and attach it if you want anyone to look at it for you vs just screen shot so can get the details of the packets.. But since your clearly working now - not sure what you expect to see?

 

When you said your other devices were working - did you actually RELEASE their ips.. A dhcp lease can last for quite some time, depending on what you set it for..  So even if the dhcp server if off you client would still work with their currently lease - only when the lease actually expires would you have problems getting a new one..

 

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