Synology VPN Server L2PT

RouterOS Beginner Basics
1

Hello!
I´m quite new to Mikrotik, but I still have running ports accessing my Synology.
But anyway: The ports 500,1701,4500 don´t want to go open for my L2PT VPN on the Diskstation.

One entry on IP / Firewall / Firewall Rules has

action: accept; chain: forward, protocl: udp; dstAddress: 192.168.0.12; dstPort: 500,1701,4500; In. Interface: ether1_WAN_xxx

3 entries on IP / Firewall / NAT as they look like

action: dst-nat; To Address: 192.168.0.12; To Ports: 1701 (500 & 4500); chain: dstnat, Protocol: udp; dstPort: 1701 (500 & 4500)

I followed the instructions on https://schweigerstechblog.de/synology-vpn-server-mit-mikrotik-firewall/ (german language).
My VPN works, when I connect inside my local network, but not, when I want to use from external.
And now, I really have no matter how to set it up to a working progress.

Thanks for any reply, Joe

2

Please share complete config:

/export file=anynameyoulike

Remove serial and any other private information.

Or try this first:

add action=accept chain=forward dst-address=192.168.0.12 dst-port=500 protocol=udp in-interface-list=WAN
add action=accept chain=forward dst-address=192.168.0.12 dst-port=1701protocol=udp in-interface-list=WAN
add action=accept chain=forward dst-address=192.168.0.12 dst-port=4500 protocol=udp in-interface-list=WAN

(or use interface in instead of list)
Any reason hosting VPN on the Synlogy instead of the MikroTik?