VPN connection over L2TP/IPSec with pre-shared key won't work

[msair]

My VPN connection over L2TP/IPSec with pre-shared key won't work with my z4 tablet. 

After a few seconds vpn is disconnected. I tried the same with pptp and it works, but that isn't what i want.

My Draytek Router has no request with L2TP in the logs.

The connection works without problems with i-phone, LG and Samsung Smartphones, all with the newest software.

Is there way to fix this problem? Thanks in advance!

[Hampus]

Hi,

It seems Draytek provides their own app for this. What if you download this app and try to connect using it: https://play.google.com/store/apps/details?id=com.draytek.smartvpn

[SergioPL1]

Check the very last option. L2TP/IPsec with 96 bit key. It was added recently and fixes issue with Synology VPN.

Also make sure PSK key is 8 lowercase alpha letters, no special characters. I didn't manage to make it work on vanilla Android too.