Unable to set up AdGuard VPN on my QNAP NAS

Hello,

I tried to set up AdGuard VPN on my QNAP NAS, in the QVPN Service application, to no avail. The NAS features the following protocols: QBelt, PPTP, L2TP/IPSec, OpenVPN, WireGuard. I selected L2TP/IPSec, as suggested in the documentation, but the setup form asks for a pre-shared key, which I don't have. So, I tried PPTP, filled out the information, and hit "Connect", but the connection times out...

Here are the screenshots:

https://ibb.co/3mmjVLST
https://ibb.co/wj6ckZq
https://ibb.co/Kxf3CZ67

When adding a new router in my AdGuard VPN dashboard, the WireGuard protocol field is marked as "Soon available". Do you know when this protocol will be available?
Do you know how I can get my NAS VPN client connected?
Thank you.