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1. IL-0349 IONOS Private Cloud in Berlin lost management access, storage and VM internet routing after a VLAN change

   IONOS Cloud2026

   Symptoms

   On 15 January 2026, network services for VMware-based Private Clouds in IONOS Cloud's Berlin location stopped working: customers lost management VPN access and traffic to and from their virtual machines. Inside IONOS, several management interfaces in the Berlin region could no longer be reached.

   Network unreachableStorage disconnected or stale mounts

   Trigger

   During a planned maintenance window to add a new VLAN to the management devices, a human error in the command replaced the existing VLANs on the trunk between the core and management devices instead of adding to them, so only the new VLAN stayed active.

   Root cause

   Operator error

   Component

   Network switchTransit gateway or network interconnect

   Contributing factor

   Excessive blast radiusNo safeguard on destructive change

   Remediation

   • Restarted the affected storage services in the final stage of recovery, which caused a brief second outage

   Action items

   • Audit the management device architecture to segment it better (target Q3 2026)
   • Evaluate and implement ways to prevent unintended VLAN changes, such as improved configuration safeguards or automation scripts (target Q1 2026)

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