an alternative technical hypothesis for investigation regarding the recent outage

The observed symptoms—including connection resets, connection refusals, timeouts, and apparent packet loss—warrant examination of inline network-security infrastructure, including Intrusion Prevention Systems (IPS), Deep Packet Inspection (DPI) appliances, or similar traffic-control systems.

A device operating inline at the network layer can potentially drop or suppress packets without generating corresponding application-layer errors. Consequently, ordinary service diagnostics may identify downstream connection failures without identifying the device or mechanism responsible. Suggested investigation:

1. Examine packet captures at both ingress and egress points of relevant network-security appliances.
2. Compare packet sequence numbers, TCP retransmissions, resets, and connection timeouts across network boundaries.
3. Inspect inline IPS/firewall drop counters, Azure Network Security Group (NSG) flow logs, ExpressRoute telemetry, fail-open/fail-closed events, and appliance health metrics.
4. Correlate these findings with the network configuration changes and routing anomalies reported during the incident.
5. Establish whether any inline network-security infrastructure was actually present and actively filtering in the affected traffic paths.

This is a hypothesis, not an established attribution. The purpose is to ensure that a potentially important network-layer failure mechanism is not overlooked by diagnostics focused primarily on application and service layers.