At the moment we configured LAN1 but we can`t get the traversal zone online although due to the firewall admin there is "any <-> any" allowed between inside network (Expressway-C) and internal DMZ (Expressway LAN1).
To which IP address the FQDN of the Expressway-E should go? LAN1 or LAN2 or Public IP?
Exp-C always points to Exp-E internal LAN FQDN in a DUAL NIC scenario.
Consider that your Exp-E has
192.168.1.210 (Exp-C IP) using internal DNS server.
172.17.18.210 (DMZ Internal LAN 1) - FQDN (Expe01.abc.com)
172.18.18.210 (DMZ External LAN 2) Nate'ed to 203.x.x.x
Traversal zone on Core will be pointing to DMZ Internal LAN 1, if you are using the TLS and certificate exchange is mandatory then point to FQDN which resolves to DMZ internal LAN 1. In this case it will be "expe01.abc.com".
In your Expressway-C traversal zone are you using IP address of the Expressway-E or the FQDN? You need to use the FQDN and also you must check that it can be resolved from the Expressway-C. And of course it should point to LAN1 address, which is the internal LAN interface.
But it can be nice if you can post a screenshot from the "System -> Network interfaces -> IP" page.
BTW, in the traversal zone page, it is stating that it's "Unreachable" or something else?