How to understand why the VPN does not contact?

Question

VPN

I'm trying to build NAT. Every node is behind NAT including the server. I chose StrongWan, configured everything according to the instructions. Yes, and I read the configs, I think everything is correct, here are the configs if anything:
Server:

conn vpn-server
  auto=add
  compress=no
  type=tunnel  # defines the type of connection, tunnel.
  keyexchange=ikev2
  fragmentation=yes
  forceencaps=yes
  dpdaction=clear
  dpddelay=300s
  rekey=no
  left=%any
  leftauth=pubkey
  [email protected]    #If using IP, define it without the @ sign
  leftsourceip=18.18.18.18 #
  leftcert=vpn_server_cert.pem  #Reads the VPN server cert in /etc/ipsec.d/certs
  leftsendcert=always
  leftsubnet=0.0.0.0/0
  right=%any
  rightid=%any
  rightauth=eap-mschapv2
  rightsourceip=10.0.1.0/24  #IP address Pool to be assigned to the clients
#	rightdns=8.8.8.8  
  rightsendcert=never
  eap_identity=%identity  #Defines the identity the client uses to reply to an EAP Identity request.

Customer:

conn vpn-client
  auto=start
  right=vpn.id
  rightid=vpn.id
  rightsourceip=18.18.18.18
  rightsubnet=0.0.0.0/0
  rightauth=pubkey
  leftsourceip=%config
  leftid=client1
  leftauth=eap-mschapv2
  eap_identity=%identity

Here is the network diagram:

And it doesn’t work, honestly, I have already gone through so many VPN servers, I also changed the VPS. I do not know what to do next, how to look for where the problem is? I do not have skills as a network administrator, do I need to prescribe something to iptables in order for this miracle to work?