I have configured IPSec VPN using a PSK to connect to my home network using the default built-in VPN settings in Android 5 on my Nexus 5. It connects correctly, but most apps don't use the connection for some reason.
For example, I cannot use either Chrome or Firefox to browse web sites hosted in the remote network. Chrome spends a long time as if it's going to load, but never does. Firefox immediately errors out saying it can't find the server. In fact, they can't load any site (like google.com etc.) while the VPN connection is established.
However, I can ping the very same host names from the phone's terminal and I can telnet to port 80 and get back a response to those same hosts when I use a telnet app, so clearly some apps are picking it up correctly.
Why isn't Firefox or Chrome able to connect to anything?