Stop automatically generating routing rules

Installing and Using OpenWrt Network and Wireless Configuration
1

Two dhcp interface, both are in the wan zone of firewall.
wwan got 192.168.1.6;
sim got 10.137.52.6;

Sometimes it automatically generate rule like this:

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.3     10.137.52.6     255.255.255.255 UGH   7      0        0 usb0

Because the destination is a specific address, this rule has a high priority
Have to delete it manually every time, otherwise you can't access 192.168.1.3 via wwan (192.168.1.6)

# /etc/config/network
config interface 'wwan'
        option proto 'dhcp'
        option metric '2'

config interface 'sim'
        option proto 'dhcp'
        option device 'usb0'
        option metric '7'

Any help would be greatly appreciated :melting_face: