This article helps you in case you have setup VPN Phase 1 and 2 correctly, but still can not the connection thorough - please check below key things;
- Quite a lot of ISPs block ESP. Since ESP is only related to encrypting traffic in the VPN, your VPN will still build up perfectly fine, but you will not be able to push traffic through the tunnel - please contact your ISP and clarify if they are blocking any ESP packets (also known as "protocol 50" - not port, it's protocol! )
- The L2TP/IPSec tunnel is working on ESP(protocol 50) and double-check ESP, IKE & NATT is allowed in security policy rule by default as below.
- If you are using PPPoE connection, than make sure to configure the same: "Configuration > VPN > IPSec VPN > VPN Gateway > WIZ_L2TP_VPN" where My address should be selected as “wan_ppp” in Interface - see the snap below;
If you are further looking for 'VPN Client-To-Site configuration', kindly have a look at article: