USB tethering changed IPV4 route table LAN metric for 4237 windows 7

I am using two network interfaces (below).

Scenario 1: Initially LAN is connected to metric = 12 of the ipv4 route table.

    IPv4 Route Table
    ================================================== =========================
    Active Routes:

    Network Destination Netmask Gateway Interface Metric
             0.0.0.0 0.0.0.0 10.12.1.2 10.12.1.13 12
            10.12.1.0 255.255.255.0 On-link 10.12.1.13 262
           10.12.1.13 255.255.255.255 On-link 10.12.1.13 262
          10.12.1.255 255.255.255.255 On-link 10.12.1.13 262
            127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
            127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
      127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
            224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
            224.0.0.0 240.0.0.0 On-link 10.12.1.13 262
      255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
      255.255.255.255 255.255.255.255 On-link 10.12.1.13 262
    ================================================== =========================

LAN ip 10.12.1.13.

When the USB tethering is connected to the system, it has changed the LAN metric to 4237. and the USB tethering gets a lower value between 4-10.

    IPv4 Route Table
    ================================================== =========================
    Active Routes:
    Network Destination Netmask Gateway Interface Metric
              0.0.0.0 0.0.0.0 10.12.1.2 10.12.1.13 4237
              0.0.0.0 0.0.0.0 On-link 101.63.220.237 6
            10.12.1.0 255.255.255.0 On-link 10.12.1.13 4487
           10.12.1.13 255.255.255.255 On-link 10.12.1.13 4487
          10.12.1.255 255.255.255.255 On-link 10.12.1.13 4487
       101.63.220.237 255.255.255.255 On-link 101.63.220.237 261
            127.0.0.0 255.0.0.0 On-link 127.0.0.1 4531
            127.0.0.1 255.255.255.255 On-link 127.0.0.1 4531
      127.255.255.255 255.255.255.255 On-link 127.0.0.1 4531
            224.0.0.0 240.0.0.0 On-link 127.0.0.1 4531
            224.0.0.0 240.0.0.0 On-link 10.12.1.13 4488
            224.0.0.0 240.0.0.0 On-link 101.63.220.237 6
      255.255.255.255 255.255.255.255 On-link 127.0.0.1 4531
      255.255.255.255 255.255.255.255 On-link 10.12.1.13 4487
      255.255.255.255 255.255.255.255 On-link 101.63.220.237 261
    ================================================== =========================

LAN IP: 10.12.1.13 4237 (metric) USB modem IP: 101.63.220.237 6 (metric)

Now the default network interface is USB Modem as it has the lowest Metric value.

Problem: Now my local application can connect to the default network interface (Metric-6), but cannot connect to the LAN network interface to access the Internet (Metric-4237).

Scenario 2: I changed the LAN metric from 4237 to 12 (or any lower value or close to the default network interface), then my local application can also connect to the LAN.

    IPv4 Route Table
    ================================================== =========================
    Active Routes:
    Network Destination Netmask Gateway Interface Metric
              0.0.0.0 0.0.0.0 On-link 101.63.220.237 6
              0.0.0.0 0.0.0.0 10.12.1.2 10.12.1.13 12
            10.12.1.0 255.255.255.0 On-link 10.12.1.13 262
           10.12.1.13 255.255.255.255 On-link 10.12.1.13 262
          10.12.1.255 255.255.255.255 On-link 10.12.1.13 262
       101.63.220.237 255.255.255.255 On-link 101.63.220.237 261
            127.0.0.0 255.0.0.0 On-link 127.0.0.1 4531
            127.0.0.1 255.255.255.255 On-link 127.0.0.1 4531
      127.255.255.255 255.255.255.255 On-link 127.0.0.1 4531
            224.0.0.0 240.0.0.0 On-link 127.0.0.1 4531
            224.0.0.0 240.0.0.0 On-link 101.63.220.237 6
            224.0.0.0 240.0.0.0 On-link 10.12.1.13 262
      255.255.255.255 255.255.255.255 On-link 127.0.0.1 4531
      255.255.255.255 255.255.255.255 On-link 101.63.220.237 261
      255.255.255.255 255.255.255.255 On-link 10.12.1.13 262
    ================================================== =========================

Permanent routes:

Inquiries

• What is the metric range (min-max)?

• Why can't the app connect to the LAN when its metric value is 4237?

Please suggest the correct way to use the metric?