Virtualization – network is not available in kvm virtual machine via Kubuntu

I tried to install a Centos guest via kvm in Kubuntu 18.10. I want to use Bridged Networking. I followed the tutorials
https://help.ubuntu.com/community/KVM/Networking and
https://help.ubuntu.com/community/KVM/Installation

Centos guest in the virtual kvm machine could not get internet access. Centos says "Connection status: not connected". How can I connect to the Internet from the virtual machine through network bridging?

The result of ifconfig in the Kubuntu host is

br0: flags = 4163  mtu 1500
inet 192.168.130.137 Netmask 255.255.252.0 Broadcast 192.168.131.255
inet6 fe80 :: ea40: f2ff: fe81: 1175 prefixes 64 scopeid 0x20
        ether e8: 40: f2: 81: 11: 75 txqueuelen 1000 (Ethernet)
RX Packets 14939305 Bytes 955671457 (955.6 MB)
RX error 0 fell 0 exceeded 0 frame 0
TX Packets 274059 Bytes 4623399678 (4.6 GB)
TX error 0 fell 0 exceeded 0 carrier 0 collisions 0

Docker0: flags = 4099  mtu 1500
inet 172.17.0.1 netmask 255.255.0.0 broadcast 172.17.255.255
Ether 02: 42: 1b: ef: 3a: a7 txqueuelen 0 (ethernet)
RX packets 0 byte 0 (0,0 B)
RX error 0 fell 0 exceeded 0 frame 0
TX packets 0 bytes 0 (0,0 B)
TX error 0 fell 0 exceeded 0 carrier 0 collisions 0

enp9s0: flags = 4163  mtu 1500
inet6 fe80 :: ea40: f2ff: fe81: 1175 prefixes 64 scopeid 0x20
        ether e8: 40: f2: 81: 11: 75 txqueuelen 1000 (Ethernet)
RX Packets 15114656 Bytes 1199723270 (1.1 GB)
RX error 0 fell 0 exceeded 0 frame 0
TX Packages 3778769 Bytes 4812661936 (4.8 GB)
TX error 0 fell 0 exceeded 0 carrier 0 collisions 0

lo: Flags = 73  mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 :: 1 prefixlen 128 scopeid 0x10
        loop txqueuelen 1000 (Local Loopback)
RX packets 2263 bytes 332780 (332.7 KB)
RX error 0 fell 0 exceeded 0 frame 0
TX packets 2263 bytes 332780 (332.7 KB)
TX error 0 fell 0 exceeded 0 carrier 0 collisions 0

vnet0: flags = 4163  mtu 1500
inet6 fe80 :: fc54: ff: fe9b: a708 prefixlen 64 scopeid 0x20
        Ether fe: 54: 00: 9b: a7: 08 txqueuelen 1000 (ethernet)
RX packets 0 byte 0 (0,0 B)
RX error 0 fell 0 exceeded 0 frame 0
TX packets 10087223 byte 610239412 (610.2 MB)
TX error 0 fell 10463 exceeds 0 carrier 0 collisions 0

wlp10s0: Flags = 4099  mtu 1500
Ether 44: 6d: 57: 5a: f9: 5a txqueuelen 1000 (Ethernet)
RX packets 0 byte 0 (0,0 B)
RX error 0 fell 0 exceeded 0 frame 0
TX packets 0 bytes 0 (0,0 B)
TX error 0 fell 0 exceeded 0 carrier 0 collisions 0

/ etc / network / interfaces in the Kubuntu host is set to

car lo
iface lo inet loopback

car br0
iface br0 inet dhcp
bridge_ports de9s0
bridge_stp off
bridge_fd 0
bridge_maxwait 0

net.ipv4.ip_forward is set to 1 in sysctl.conf

virsh edit displays the kvm network settings as