RT-AC86U VPN Servers... No L2TP option?

I thought I'd explore my intention to enable a VPN server on my new ASUS Router (owned less than 1 week) so that I could connect my Windows 10 phone to my own VPN when using mobile hotspots. I read enough of the VPN forum section to know that PPTP was a bad choice of VPN server, and OpenVPN is not an option on a windows phone.

I saw lots of folks suggesting L2TP/IPSec over PPTP, but the default ASUS options are only PPTP and OpenVPN for server choices on my RT-AC86U... although VPN Client...

RT-AC86U VPN Servers... No L2TP option?