I researched L2TP/IPSec VPN client connection setup on Windows10.

I referenced the following article for basic VPN setup methods:

• Windows10のL2TP接続　■セカイVPN■

Usually, the above article should be sufficient to complete the setup successfully, but if you’ve built a VPN Server on Mac OS, you’ll need another configuration step. Please refer to the following article for details:

• OS X Server：Windows から VPN サービスに接続する方法 - Apple サポート

I’ll write a separate article about the specific troubleshooting steps I took.

That’s all from the Gemba.