Fair enough, truthfully there’s no real support for that here, since the dedicated server launcher is not even part of the game, basically one of their devs made it in their spare time as a “trying to be nice to users” bonus 
Anyway @rigultru did sort of very vaguely touch on the issue
“forwarded to the destination server”
So basically you’re running an internet service on a device with two separate network interfaces. One service can only listen on one interface.
If you look at the instructions provided for the dedicated server launcher, that multihome checkbox is for the scenario when you’re a hosting company and you want to run multiple servers off the same machine (shared server) it allows you to pick interfaces more explicitly (booting up the server with the ip address being in the command line)
The reason it let you connect after checking that is because the server now started up and started listening on that interface instead of the other one.
What you actually want to do if you want to listen on multiple interfaces is
- pick an interface say your real one with the ip 192.168.0.2
- start up the server on that interface as normal
- then route traffic from the other interface on the same port to this interface.
So essentially you need some form of a routing software (windows does have a built in command line one if I remember right) and route traffic from 26.13.238.231 to 192.169.0.2 on port 7777
Edit: keep in mind you still need to have your firewall and port forwarding configured on your real router too so your server is accessible from the outside in the first place (connect to router web interface, and forward the game port to your computer’s internal IP 192.168.0.2 - obviously setting up a static DHCP so your computer always gets that IP helps) the article where they introduced the server launcher explains this part more with pictures and stuff Conan Exiles Dedicated Server Launcher (Official Version: 1.7.2 / Beta: ----)