After setting up a VPN server, you find that other CVMs cannot be accessed?

problem description

uses ipsec-vpn to build a VPN server, and then the local configuration of VPN Client, is also dialed, but it is not possible to access other servers in the private network. What is the reason for this?

after adding VPN, one more network card is added:

ppp0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1280
inet 192.168.42.10  netmask 255.255.255.255  destination 192.168.42.1
ppp  txqueuelen 3  ()
RX packets 4644  bytes 2693495 (2.6 MB)
RX errors 0  dropped 0  overruns 0  frame 0
TX packets 4569  bytes 777694 (777.6 KB)
TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

The

server network segment starts at 10. Do you want to change the configuration?