Having an issue with NAT

Rob Williams

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Staff member
Moderator
About a month ago, my PC stopped being discoverable on the network. I couldn't connect to it via my phone or another PC. When I use the troubleshooting option in Windows, I get this error:

More than one device is performing network address translation (NAT).

What's causing this? I have VMware installed, which setup two faux NICs, but that was installed from the get-go, and I've never had this problem with it before. This PC connects to a NETGEAR router which connects to a Siemens (ISP). Is the problem with one of those?

Any help would be appreciated. I spent hours on trying to fix this to no avail, and I'd love to be able to connect to the PC again.

Thanks!
 

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Greg King

I just kinda show up...
Staff member
Im in the middle of shitty homework but am more than happy to help you out tomorrow.

For starters, disable VMware. Just disable the service and shut down the program. Does the problem go away?
 

Rob Williams

Editor-in-Chief
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I can't do that atm as I am running it with something I can't shut down, but once I am able I will give that a go. Thanks man :D
 

Greg King

I just kinda show up...
Staff member
Im in the middle of shitty homework but am more than happy to help you out tomorrow.

For starters, disable VMware. Just disable the service and shut down the program. Does the problem go away?

Then why did it just start? My logic is lame.
 

Rob Williams

Editor-in-Chief
Staff member
Moderator
I am not having a problem with a VM, if that's what you mean. I just mentioned that the only program that I have installed that has anything to do with the network -is- VMware, since it sets up those faux NICs. I've had VMware installed forever though and have never had this sort of issue before.
 

TheCrimsonStar

Tech Monkey
From what I can see, you should check to see if both your router AND cable modem have NAT enabled. If that's the case, then there's your problem. You probably already know this, but I'll put it here anyway for explanation's sake. Most routers and modems use NAT so that multiple devices on the network can have separate internal IP addresses while sharing a single external one. If both your router and modem are trying to use NAT, then your modem is making an internal IP address (192.168.etc) for your router and that router thinks that internal address is the external. It's trying to make another internal IP and it's getting confused. Some ISP's do their own NAT, and if yours started doing that a month ago, you'll probably have to call them up or switch ISPs (hopefully that's not the case)

Found this, maybe it'll help.

http://windows.microsoft.com/en-SG/windows7/Network-address-translation-How-to-avoid-common-problems
 

Greg King

I just kinda show up...
Staff member
From what I can see, you should check to see if both your router AND cable modem have NAT enabled. If that's the case, then there's your problem. You probably already know this, but I'll put it here anyway for explanation's sake. Most routers and modems use NAT so that multiple devices on the network can have separate internal IP addresses while sharing a single external one. If both your router and modem are trying to use NAT, then your modem is making an internal IP address (192.168.etc) for your router and that router thinks that internal address is the external. It's trying to make another internal IP and it's getting confused. Some ISP's do their own NAT, and if yours started doing that a month ago, you'll probably have to call them up or switch ISPs (hopefully that's not the case)

Found this, maybe it'll help.

http://windows.microsoft.com/en-SG/windows7/Network-address-translation-How-to-avoid-common-problems

Good write up. Thank you for beating me to it :)

I can't however, imagine having to switch ISPs over something like this, assuming the scenario you are suggesting is true.
 

Rob Williams

Editor-in-Chief
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Moderator
Alright, I blanked on mentioning something last night. I have multiple PCs connected to that router, and no other one than this has the problem of being discoverable on the network. The NAS is fine, the laptop is fine, and the benchmarking PCs are fine. It's just this PC. I can also discover myself when in Linux. It's just Windows that's being a bitch.
 

DarkStarr

Tech Monkey
it means VM ware screwed the network adapter lol

Well, in that case I would take a look at the real adapters settings make sure its all on auto (unless its not supposed to be) but anyways VM stuff can be a massive PITA due to the damage it can do. I have seen windows installs hosed by some sort of spectacular VM failure (crazy that it would happen but I guess it does happen).
 

Kougar

Techgage Staff
Staff member
What DarkStarr said. I'd nuke the Windows OS drivers for the network adapter and reinstall them (with a newer version too since there almost always is one out), and cross my fingers that will work.

Otherwise you'll probably have to temporarily remove Vmware while you reinstall them, make sure they work, then reinstall Vmware.
 

Rob Williams

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You guys aren't going to believe this =/

It was Windows Firewall that was causing the issue. I don't usually keep it enabled, but after my reformat, I didn't think about it. Lo and behold, it was blocking all incoming connections for -some- reason (I couldn't figure out how to change that), so it's easier just to disable it.
 

DarkStarr

Tech Monkey
ROFLMAO nice..... my windows firewall is always on and I never have an issue. Looks like something changed a setting it shouldn't have.

Also, don't get me started on how horrible it is to change stuff with the windows firewall, such a huge pain and your never quite sure if it worked or not.
 

Rob Williams

Editor-in-Chief
Staff member
Moderator
I never have an issue with Firewall either, so I'm not sure what the problem is. I had Firewall enabled from the get-go, and it was only a month into the install that this problem created itself. So dumb...
 

Kougar

Techgage Staff
Staff member
I've never once had to mess with the Windows Firewall for any sort of reason, except once with Borderlands because it was using ports in addition to those it had created rules for. I can't honestly remember any other time since I installed this OS that I've had a problem.... as DarkStar said, something definitely mucked with your OS Firewall settings. ;)
 

Rob Williams

Editor-in-Chief
Staff member
Moderator
I've never once had to mess with the Windows Firewall for any sort of reason, except once with Borderlands because it was using ports in addition to those it had created rules for. I can't honestly remember any other time since I installed this OS that I've had a problem.... as DarkStar said, something definitely mucked with your OS Firewall settings. ;)

This is the first time to my knowledge I've ever had issues with Windows Firewall also. And I am not sure what mucked them up given I've installed barely any software since the last time the network worked fine.
 
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