L2TP or SSTP VPN broken after ISP modem swap

Minimal guidance for messy support realities.

Scenario

Remote workers lose VPN access after a modem or router swap at home or at the office.

Recommended Resolution Path

  1. Verify port forwarding, passthrough, and public IP changes after the equipment replacement.
  2. Test whether the office firewall still presents the expected certificate and listener.
  3. Check MTU and fragmentation only after core routing is proven.
  4. Document the known-good WAN edge settings to accelerate future recoveries.

Technician Notes

Confirm the business impact, document the root cause, and capture any preventative follow-up in the PSA or client knowledge base.