IPSec remote access with xg firewall

Hi,

I want to configure IPSec remote access on a XG FIREWALL VM v18.0.4 that i am currently using as a smtp gateway for our mail server. I configured IPSec to use the same public address and when i try to connect to the firewall using the sophos connect client a get the error PORT UDP IKE IS BLOCKED.

my firewall rules are as follow : 

1. A firewall rule to allow connection to our mail server :

source zone : WAN   source networks : ANY

destination : LAN destination networks :  public address 

services : IMAP IMAPS HTTP HTTPS SMTP SMTPS

2. A NAT rule for the rule above to forward it to the mal server private address.

3. a rule to permit traffic to internet from our mail server.

for me i am thinking that the firewall is sending my vpn connection request to the private ip address thats why is telling me UDP PORT IKE IS BLOCKED. or i just cannot use the same publich ip address for both DNATing our mail server and IPSec vpn remote access.

THANKS FOR HELPING.