ip route add default via 19216812339 dev eth0 src 17218052Error Invalid prefsrc address

The error message suggests that the source address specified in the command is not valid. The source address (172.18.0.52) must be an IP address that is assigned to the interface specified in the command (eth0).

To fix the error, you can try the following:

1. Check the IP address assigned to the eth0 interface using the command "ip addr show eth0". Make sure that the source address specified in the command is a valid IP address that is assigned to the eth0 interface.

2. If the IP address assigned to the eth0 interface is not correct, you can assign a new IP address using the command "ip addr add <ip_address>/24 dev eth0".

3. Once you have a valid source address assigned to the eth0 interface, you can try the ip route command again with the correct source address. For example: "ip route add default via 192.168.123.39 dev eth0 src <valid_ip_address>"