When connecting a L2TP tunnel with a windows client, normally all internet traffic will go trough this tunnel. To spare bandwidth and therefore keep the internet traffic out of the L2TP tunnel follow the guide below..
On windows PC, we need to uncheck Use default gateway on remote network, and add routing on CMD. Please follow below steps.
You can implement the split tunnel configuration by following the steps below.
1. Go to Start > Control Panel > Network and Sharing > Change Adapter Settings.
3. Switch to Networking Tab, select Internet Protocol Version 4 (TCP/IPv4) and click Properties to view the Properties window.
4. In the Internet Protocol Version 4 (TCP/IPv4) properties window, click Advanced.
5. In the Advanced TCP/IP Settings window under IP Settings tab, uncheck Use default gateway on remote network.
After that please add the routing on CMD on PC
Here is example, "route add 192.168.1.0 mask 255.255.255.0 192.168.100.33"
"route add (local policy) mask (subnet of local policy) (the IP address you get after VPN established)"
the"192.168.1.0" is local policy ,and "mask 255.255.255.0" is local policy subnet. "192.168.100.33" is the IP address you get after VPN established.