Windows 10 doesn't get WAN when connecting a secondary LAN

[Bytorane]

Hello

I'm doing some advanced troubleshooting and configuration of an unrelated network device which I'll be connecting to a seconary router via WiFi, but I don't want that device to be connected to the internet initially because it disrupts the troubleshooting.

My PC1 has two network ports. NIC1 is Intel Gigiabit, NIC2 is Realtek 2.5 Gigabit
PC1 currently uses a quick relatively unconfigured Windows 10 installation (I could boot into one of my linuxes, but for now I want to try a windows-only app during troubleshooting)
I have the primary Router 1 normally connected to PC1
I have Router 1 connected to Router 2 and Router 2 is configured on a different subnet for this exact purpose to work as a secondary one.

Router1 LAN is plugged in PC1-NIC1
I want to control the secondary router and the tools installed on the router from my PC1, so I plug in Router 2 LAN into PC1-NIC2
I don't want PC1 to deal with WAN over Router2, only LAN control stuff, PC1 should continue to use Router1 for WAN normally.
I have blocked WAN access in Router2 for PC1, so PC1 shouldn't be able to connect to Router1's LAN via Router2, Router1 configuration remains unchanged.
To repeat, Router2's WAN is a LAN address given by DHCP from Router 1.

Windows 10 or who, for some reason switches by default to regard the Router2 as the only WAN source, which causes loss of internet connectivity for PC1.
Despite both networks connected and both LANs working without an issue, I'm able to control both Routers, it doesn't see WAN over Router1 anymore.

I'm not that big of an network enthusiast to immediately know why this is so or where the responsibility of setting the priority and behavior up is.
Perhaps is some kind of a static routes things, and a side-effect of both networks leading to the same LAN and then actual ISP WAN.

Doesn't mean necessairly I need this kind of a setup, if someone has a better idea I'm open.
The obvious other alternative is to connect to Router2 via it's WAN IP but I'd have to setup WAN administration access and open a potential security gap, however for the limited time I probably don't have to be that concerned, and given that Router1's firewall is in the way it probably would block anyone trying to get direct link with Router2 but I don't want to speculate or make up conclusions about networking.

 

[Solaris17]

This is hard to follow because there is a lot of info that doesn’t matter and it is written and not diagrammed.

But from what I understand of your goal and your current situation you can get around this by disabling DHCP on PC1 NIC2. Go to NIC2 and simply set a static IP and subnet that matches that of router2 and the device on router2 that you wish to communicate with.

setting DNS and a gateway is not necessary on NIC2 don’t set them.

just the subnet and IP.

 

[Bytorane]

just the subnet and IP.

That did the trick of "restoring WAN" over Router1, but I can't access the adminitration for Router2 via 192.168.2.1 either, not an auth issue, I can't ping it at all.

Upon connecting Router2 to NIC2, windows10 launches default browser going to www.msftconnecttest.com/redirect trying to do something, ends up with some error page on Router2 because I'm blocking PC1 WAN Access.

 

[Deleted member 242843]

Solaris is right, and has given you the correct answer.

Some food for thought:
https://www.tenforums.com/tutorials...apter-connection-priorities-windows-10-a.html

 

[Bytorane]

Solaris is right, and has given you the correct answer.

Some food for thought:
https://www.tenforums.com/tutorials...apter-connection-priorities-windows-10-a.html

But, it was the other way around ... the initial suggestion didn't work, it also made LAN2 not-functional, but your suggestion about network metric is what worked now. I put the Network 2 on NIC2 to a higher metric 35 instead of 25. Both were 25 automatically.

A funny twist was that I forgot ... NIC's have their own MAC Address, I don't know why the heck does PC1 show up with MAC1 from NIC1 on it's LAN ... and not with the NIC2's MAC2 which is how they're connected. It could be some kind of a cahce issue on router2's FW, I interchanged the NIC's previously not really paying attention which NIC to connect when I was doing something else with the same PC.

This is probably a separate issue I'll troubleshoot tomorrow, time for sleep.

 

[Solaris17]

Mac’s are held that’s literally how L3 switching works. It will release it eventually. I’m sure you can reset the arp table on your router, reboot, reset, time or otherwise. But it will vary and I’d be surprised if a consumer routers manual told you how point blank.

 

[Bytorane]

I'm somewhat aware of that arp cache, and I had to deal with it in the past, but in this case it was just my mistake seeing it wrong.
I double checked, MACs pan out correct, I was just mixing it up. Though it's entirely possible it refreshed by it self at some point and I didn't notice, didn't memorize the numbers exactly.