Summary

On July 17th, 2025, starting around 05:30 GMT+2, we experienced a partial connectivity issue affecting traffic to the endpoint 5.83.150.1. A portion of external networks was unable to reach some prefixes including 5.83.150.0/24, while others remained fully functional.

Initial observations pointed towards a potential BGP routing problem, but external route propagation appeared fully intact across all monitors.

Root Cause

The issue was caused by a malfunctioning SmartMitigate DDoS filtering node within the upstream provider's infrastructure. The affected host had stopped forwarding traffic.

As a result, incoming traffic that was routed through this specific mitigation node was effectively dropped, leading to asymmetric reachability depending on which SmartMitigate host was assigned.

This incident was not related to our own BGP announcements or configurations.

Resolution

The upstream provider identified the faulty SmartMitigate host and removed it from operation. Immediately afterward, traffic flows normalized and full connectivity to the affected prefix was restored. This occurred around 09:20 GMT+2.

Impact Overview

Affected Prefix: 5.83.150.0/24
Root Cause: Faulty SmartMitigate (DDoS filter) node
BGP Status: Unaffected – all routes remained correctly announced and visible
Duration: ~3 hours 50 minutes
Impact: Partial traffic loss (limited to traffic routed via the affected SmartMitigate node)

Current Status

Connectivity has been fully restored. The root cause has been addressed at the upstream provider level. No further disruptions are expected related to this issue.

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