Using Dual NICS under Win7 for normal & VPN Internet connections?

Thenin · 11 Mar 2015

As requested, here are the answers to the basic Network Config questions:

1) My issue is with wired networking (gigabit ethernet)

2) ISP: Comcast

3) Cable broadband Internet

4) Modem: Motorola Surfboard
Router 1: TP-Link Archer C8 Dual-band Gigabit & wireless
Router 2: Belkin N600 Dual-band & wireless

5) Firewall & Antivirus disabled for this process

The rest are configured correctly.

Here's the issue I need help with: I have a few machines that have dual NICs. My intention is to use the second NIC on each to connect to a second router that's connected to my cable modem, such that I can use one NIC for ordinary Internet browsing, etc and the second NIC for use with a *software* VPN service (requiring configuring one of my browsers (either Opera or a portable Firefox installation) to use the proxy at all times).

Since both NICs and both routers need to connect to the same cable modem, I have the modem connected to a switch to distribute the single modem signal to both routers. Q1: Is this correct or is it a mistake?

Naturally, I have setup the two routers to use two different subnets and gateways and IP address ranges. The ordinary-use one I've set the gateway IP to 192.168.1.100 (with the IP range starting from 1.101 ) and the second router's gateway I've set to 192.168.2.100 (with the IP range beginning at 2.101).

(Note that I usually disable DHCP and use static MAC<->IP address binding, since I essentially never need to allow for new networked devices with unknown MAC and/or IP addresses. However, I've tried enabling it and allowing automatic IP address assignments as part of my troubleshooting process, but it didn't help).

Here's the problem: With BOTH NICs enabled under 64-bit Windows Pro SP1, neither one can connect to the Internet. But if I disabled either one, the other connects perfectly! Q2: Why? What am I doing wrong?

Now, I've read some tips from others about how unlike XP, Windows 7 doesn't really enjoy trying to deal with two NICS and subnets, etc, and that it's possible one has to configure some routing tables or something of that sort. But I don't know if I have to do that within Windows 7 or if I can do it in the appropriate router. Either way, I'm willing to try, but I need guidance, so that's Q3, please.

I've also read that it's helpful under Windows 7 to connect the two routers together to avoid the need to alter routing details, but isn't what I've already done -- connecting the modem via switch to both routers -- good enough? That's my Q4.

Can some expert out there help me out, please?

logicearth · 12 Mar 2015

So I'm going to ask you a question. Why? Why do you want to setup such a complicated network, that will not even work? You can do multiple things with one connection, normal browsing and VPN though one connection. Using two connections for two different purposes will not bring any extra benefits and as you have found out, does not work.

Now as for why you cannot connect to the internet with both active, Windows just doesn't know which network it should try and use, they are two district networks but both have internet access....which do I use?! *Amendment: You might get it to work if the second NIC does not have a gateway set. Just IP and subnet.

The point of having two NICs is for fallover, load balancing, or multiple networks (without internet access on one of them). Not...for whatever it is you dreamed up.

The only real way you are going to get this to work is if the VPN router does not advertise there is internet on the other end. However, I cannot really tell you how to make this work, even tho networking is one of my things, I would never in a millions make something as complicated as this. I live by the policy: KISS, for this kind of stuff.

Thenin · 12 Mar 2015

okay