Service Notification - Update #1

Date: 23 January 2026 16:45 AEST Status: Ongoing - Root Cause Identified Affected Servers: cloud3 (101.0.86.67), cloud4 (101.0.65.98)

Update

We have identified the source of the connectivity issues affecting some customers.

The problem has been isolated to a specific upstream routing path within our datacenter's transit network. Traffic routed via this path is experiencing an MTU limitation causing large packets to be silently dropped. Traffic routed via alternate paths is unaffected, which explains why some customers experience issues while others do not.

This is affecting customers on multiple ISPs including Telstra and Optus.

Current Status

We have implemented a server-side workaround which resolves connectivity for affected customers. We have escalated to our upstream provider with detailed diagnostic information identifying the specific network path involved.

Next Update

We will provide a further update once we receive a response from our upstream provider or when the issue is resolved.

Summary

Some customers connecting via Telstra fixed-line internet services experienced intermittent connectivity issues when accessing websites and email services hosted on cloud3. Affected users may have observed connection timeouts when loading websites or connecting to email, despite being able to ping the server successfully.

Root Cause

A routing change within Telstra's network introduced an MTU (Maximum Transmission Unit) limitation on the network path to our server. The affected network equipment was silently discarding packets larger than approximately 1200 bytes rather than sending the appropriate ICMP fragmentation messages that would allow our server to automatically adjust.

This type of issue, known as a "PMTU black hole," causes TCP connections to establish successfully but then fail when transferring data. The problem only affected customers whose traffic was routed through the affected Telstra network path.

Resolution

We have implemented TCP MSS clamping on the server to limit outbound packet sizes. This ensures reliable connectivity regardless of MTU limitations on upstream networks.

Impact

• Customers on other ISPs including Starlink, Optus, and TPG were unaffected
• No data was lost
• No server configuration or hardware was at fault

We apologise for any inconvenience caused. If you continue to experience connectivity issues, please contact our support team.