Sophos DDNS is not Updating

Question

I have a XG 106 at a customers company. 
 He wants to connect via VPN to his computer from home. ( i wanna use sophos connect client) the problem is that the DDNS "is not available" and i cant find the issue. 
 
 Here's the setup in his office 
 ISP Router (192.168.1.1)(Port1) -> Sophos WAN(Gets adress via DHCP) ISP Router(192.168.1.1)(Port2) -> Dumb Switch -> Sophos Lan interface (192.168.1.253) unfortunately it is not possible right now to have the usualy physical Router -> Sophos -> LAN seperated setup. 
 i need to connect both LAN and WAN interface to the router. 
 
 i configured a port forwarding on the isp router to the wan interface of the sophos xg. the forwarding to the sophos is configured as "exposed host" cause only port forwarding did not work in my first try so here are my screenshots with the error message

any suggestions?

Deo Angelo Lim · Answer

There are two issues I have seen on the set up. 
 
 1. The LAN and WAN network are the same it should be different otherwise it might have conflict on the traffic internally and externally. Try to change you WAN Network, adjust it on the router. Example: 192.168.2.1/24 
 
 2. The DHCP Ip that the router is providing for your WAN is not a public ip. If you are going to use it as a VPN or Port forwarding it should be Public IP not a private one. I suggest to contact your ISP provider and make it a bridge set up on you WAN to get a public ip if possible.