@rub75f
So you set up an IPSec server on pfSense with intention to connect to internal devices. No, there should be no more to do.
However, it seems your mobile device cannot connect.

So do you have a public IP on pfSense WAN?
Or is there a router in front of it? If so how did you set up NAT on the router?

Do you have a static public IP or a dynamic?

On pfSense WAN you will have a firewall rule allowing the IPSec packets. So check if any packet hit the rule.

@Konstanti

I attach a network diagram of my setup to make it clearer.

This is what is weird, when I connect to the VPN from my phone on 4G (option 1 in the attached diagram), I don't get errors any errors just timeouts. I can access everything on the internal LAN and internet, except, I cannot login into certain webservices. When I enter my password and press login, it just stalls - the browser says it is "thinking / loading" and then nothing happens. After a long time I get a "Server not found" error in the browser.

However, when I am on my phone on the internal wifi over the VPN (option 2), then I click login and get redirected instantly to the dashboard of the webapp. I can also reach the webapp from outside my network as I have a reverse proxy (option 3), and this works fine.

The reason I want to set up the Mobile IPSec VPN is that I want to close down the reverse proxy I have set up so that I can only access my webservices over the VPN and not anymore expose them directly to the internet.

0_1549268966959_7037c544-acec-48e5-bea3-45c0e02ae4b2-image.png

That's it! Thank you so much!