As I had mentioned I am inexperienced in TP-Link products.
My scenario is the following:
I have a TL-R605 omada router which is connected to a DSL router in port WAN, and in port LAN of router is connected in port 8 of a TL-SG2008P omada switch. The TL-SG2008P omada switch is connected to a hardware controller omada OC200 in port 1, and in port and 3 are connected two Access Point.
Configuration L2TP via omada cloud:
I give a name: testl2tp
I select Purpose: Client-to-Site VPN
I check the status enable
I select Local Networks
I set a Pre-Shared Key
I select WAN links
I set an IP Pool which is different than other subnets which is created (192.168.110.0/24)
Also I add a user.
On a windows laptop, I set a VPN and I complete the appropriate fields.
On IP Server, I put the public IP of the DSL modem which is connected the TL-R605 omada router.
Nothing works and the message which appears is "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiotations with the remote computer"