Enable L2TP VPN Ports

I must get my employer’s L2TP-IPsec VPN working over my home VTR connection so I can log in remotely without drops or authentication errors. My setup includes a modem from the ISP, a separate router, and a small firewall appliance; the VPN will be used on a Windows laptop.

Here’s what I need from you:

• Identify and open the required L2TP-IPsec ports (UDP 500, 1701, 4500, plus ESP) on the router/firewall and confirm they pass through the modem correctly.
• Adjust any NAT-T or pass-through settings so Windows negotiates the tunnel successfully.
• Check Windows-side parameters (pre-shared key, authentication, routing) and confirm they align with the company’s specs.
• Provide a short validation report showing the port-checking results and a successful VPN session, or flag any ISP-level blocks that still need escalation.

If additional port-forwarding rules or firmware tweaks are necessary, guide me through them in a live session (AnyDesk, Zoom, or similar). I’m not certain whether manual forwarding is required, so your first task will be to diagnose and then implement the cleanest fix.

Once the VPN signs in reliably and I can ping corporate resources, the job is done.