Windows machine not routing traffic to correct NIC

SAS

1/2/24, 1:42 PM

I have a windows laptop with two NICs. One is a wireless interface (used for general internet usage), the other is cellular modem using a SIM which makes it a part of private network (IP 10.100.100.12)

When both these interfaces are enabled, my routing table looks like

Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0      192.168.0.1    192.168.0.104     35
     10.100.100.8  255.255.255.248         On-link     10.100.100.12    257
    10.100.100.12  255.255.255.255         On-link     10.100.100.12    257
    10.100.100.15  255.255.255.255         On-link     10.100.100.12    257
        127.0.0.0        255.0.0.0         On-link         127.0.0.1    331
        127.0.0.1  255.255.255.255         On-link         127.0.0.1    331
  127.255.255.255  255.255.255.255         On-link         127.0.0.1    331
      169.254.0.0      255.255.0.0         On-link    169.254.88.114    281

The problem is, when I try to ping some device on the cellular network e.g) 10.100.100.50 I get no response. When I use trace route I see this,

C:\Windows\system32>tracert 10.100.100.50

Tracing route to 10.100.100.50 over a maximum of 30 hops

  1     4 ms     3 ms     3 ms  kabelbox.local [192.168.0.1]
  2    17 ms    16 ms    16 ms  83-169-183-49-isp.superkabel.de [83.169.183.49]
  3     *        *        *     Request timed out.
  4     *        *        *     Request timed out.

The packets are going to my internet router (connected via WiFi) which should not be happening. If I turn off my laptop WiFi, then I can properly reach devices on the 10.100.** network.

How can I make sure that even with both these interfaces turned on, I can use the WiFi for my general internel usage and the cellular just to access 10.100** ips?

1 + 1

windows

routing

bjoster

1/3/24, 8:13 PM

10.100.100.8/29 does not include 10.100.100.50, so IP routing is sending those packets the the default gateway. Triple check the subnet mask(s) of your client(s).

Score:0

Server

Greg Askew

1/2/24, 3:56 PM

There isn't a closer route to 10.100.100.50. The route for 10.100.100.8/29 has a usable range of 10.100.100.9 - 10.100.100.14. If you want a route to 10.100.100.50 you should create it.

+ 4

SAS

1/2/24, 4:17 PM

still then I should be able to ping my own ip (10.100.100.12), but even that is going to the wrong interface

Greg Askew

1/2/24, 4:23 PM

@SAS: What "devices" are on this network?

SAS

1/2/24, 4:30 PM

raspberry Pi(s), if just turn off my WiFi, then I am able to reach them so the problem is definitely in my routing. Also I noticed when I turn off wifi, windows auto adds this route Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 10.100.100.13 10.100.100.12 257 which somehow fixes the issue (as long as wifi remains off)

Greg Askew

1/2/24, 4:42 PM

@SAS: You may want to update the question with address(es) that are in the correct range.

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EN: Windows machine not routing traffic to correct NIC

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