Site2Site Tunnel with overlapping IP Ranges (Part 2)

Hello Gernot,

Thank you for contacting the Sophos Community!

If you are using NATing to get to the other side because of overlapping then the Server will not be able to see  the Original Address.

Regards,

Thanks for answer. That's was my question: Is there any way to establish that tunnel without NAT?

Can you get us a Network Map? 

Site2Site Tunnel:

old department (172.20.20.0/24) <-> SG 172.20.20.1 (internal)
                <-> Internet <->
                            XG 127.20.20.1 (internal) <-> new department ((172.20.20.0/24)
                                                                             
Works when NATted as described in

(https://support.sophos.com/support/s/article/KB-000035848?language=en_US)

NAT will only create a new Network (For example: 172.21.20.0/24). 

So if a client in the old network pings 172.21.20.1 it will be translated to 172.20.20.1. 

This network solution is not to migrate existing networks without any flaws.