ISP H/W T3200M provides VPN L2TP Application to presumably forward inbound VPN traffic to the WAN1 IP of the TL-R6000VPN (set for Client to VPN L2TP PassPhrase Username PWD) ... Using W7 or W10 VPN settings both fail to connect stating "The L2TP Connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer" ... ISP Forum says to Bridge the T3200M Port 1 but this has 2 problems <1> it only provides for PPTP <2> the T3200M becomes unavailable for management from Port 1 ... can someone provide a diagnosis of what negotiation is failing so this issue can be resolved ... here is the T3200M Firewall status ... (possibly the T3200M L2TP Application is expecting a PC rather than a router VPN or maybe Port 50 forward is required ... the protocol for port 50 isn't available on the T3200M)