L2TP passthrough ePMP SM in NAT mode

Hi there,

I'm trying to get working a l2tp server using a routerboard behind a SM ePMP Force180 working in NAT mode (PPPoE).

I've configured port forwarding with ports 500 / 1701 / 4500 both UDP & TCP through the routerboard but it doesn't work.

It seems both protocols AH and ESP are not forwarded.

This solution work perfectly with PPTP VPN but mac and win10 doesn't support PPTP anymore. I'm trying to do this for one of our customers but it doesn't work.

The only way it can work is changing ePMP config in bridge mode and then let routerboard do the PPPoE. Obviously L2TP vpn works perfectly (so it's configured correctly!).

Does anyone knows a solution for this problem?

Best regards,



I am not sure if it will help, but you may find the following article useful:




Wonderful!!! Applying this setting over Windows 7 client, now VPN L2TP works and I can connect to the routerboard even behind Force180 in NAT mode.

Thanks a lot!!!!

Kindful regards,