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I need a computer to see and communicate with 2 totally different networks.

I have a computer that I have on an existing network.  I need for it to see another network too.  I installed an additional NIC.  On the primary NIC I have a IP address, subnet mask and gateway.  On the second NIC I need to have also an IP address, subnet mask, and gateway.  If I put the second gateway in, my computer no longer will talk to the internet.   By the way, the second network does not have an internet connection, but I have to have the gateway to talk to the equipment on the 2nd network.  How can I make both of these NICS work on the same computer without messing up my main NIC?
Network ArchitectureWindows XPWindows Networking

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8/22/2022 - Mon

I was going to say that you might try not putting in the gateway on the second NIC, but apparently you need that.  Do you have to be able to talk to both at the same time?  If not, you can change the route metrics on the PC to temporarily make the second NIC the hot NIC and then switch back when you want to go the other direction. I do that on my home PC...I have one NIC that points to my home network across my internal router and to my Cable modem. My wife has a separate network in our home for her work. I've placed a wireless AP on that line and I have a wireless card in my PC that allows me to get to it. I have written two batch files that will do "route change" statements to make the wireless either the preferred route or the other way the preferred one.
Rob Williams

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use the command line to change the metric on the gateway.  Tha command is route.
If you do a route print you will see at the end of the heading is metric. the smaller the number the higher the priority.  Open your command prompt and type in route for more information
Rob Williams

Metrics with gateways don't work with Windows and they are for fail-over. When the fist gateway is unavailable, for a split second, it will switch over to the higher metric gateway, as it should, but it will never switch back, as it is supposed to. However, afraid that will not address the routing issue.
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James Murphy

Actually changing the metric does work as I said in my comment above, but only if you want to go only one direction at a time.  I've set up my system with IP, mask, and default gateway on both NICs and it works just fine...as long as I only want to go one direction or another. I've confirmed that the lower metric becomes the default route and it's easy to change back.  But, as you correctly stated, to be able to go both directions at the same time, you can only have one default GW and you need to control the flow by entering in the proper route statement.
Rob Williams

My apologies, yes metrics would work if you want to manually change them back and forth each time you want to switch networks.

I need to be able to run on both networks at the same time.  I will try the routing command from command line.
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RobWill's instructions should work just fine. I run a server at my company that has dual NICs and I have the exact setup that he suggested using. One NIC is complete in its setup and the other doesn't have a GW.  Then I use a route command to make all traffic bound for that network route through the proper NIC. Works well.

Nukebug... did anything here solve your problem?

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