How did you access the router when the tunnel failed — via external IP?

If the tunnel has fallen and there is no direct access to the internal network, the usual approach is to access the router via its external IP address, if it is accessible from the internet. For this, the router must be configured to accept SSH or another management protocol on the external interface.

If direct access via the external IP is not possible, alternative methods can be used:

• Connecting through a backup communication channel (e.g., modem or LTE).
• Using out-of-band management (e.g., console port through special equipment).
• Access via VPN or another tunnel, if it still works.

It is important that the infrastructure provides such access methods for recovery of communication.