All times in BST (London).
At 15:18, we received messages from our alert system which reported networking issues to our Amsterdam hosts.
The on-call engineers were reached immediately who began investigation.
At 15:20, we had discovered that a misconfigured job had dropped an IPv4 and IPv6 route from one of the VM host machines.
At 15:22 the networking tables were restored and VMs continued connectivity as expected.