Если пришло такое вот сообщение:

There is an undeclared Mac address going through your server's port:

MAC: 52:54:00:39:E5:64

Aug 30 00:28:39 GMT: %PORT_SECURITY-2-PSECURE_VIOLATION: Security
violation occurred, caused by MAC address 5254.0039.e564 on port
GigabitEthernet0/28.
Aug 30 00:28:39 GMT: %PORT_SECURITY-2-PSECURE_VIOLATION_VLAN: Security
violation on port GigabitEthernet0/28 due to MAC address
5254.0039.e564 on VLAN 392
Aug 30 00:30:39 GMT: %PORT_SECURITY-2-PSECURE_VIOLATION: Security
violation occurred, caused by MAC address 5254.0039.e564 on port
GigabitEthernet0/28.
Aug 30 00:30:39 GMT: %PORT_SECURITY-2-PSECURE_VIOLATION_VLAN: Security
violation on port GigabitEthernet0/28 due to MAC address
5254.0039.e564 on VLAN 392
Aug 30 00:31:06 GMT: %PORT_SECURITY-2-PSECURE_VIOLATION: Security
violation occurred, caused by MAC address 5254.0039.e564 on port
GigabitEthernet0/28.
Aug 30 00:31:06 GMT: %PORT_SECURITY-2-PSECURE_VIOLATION_VLAN: Security
violation on port GigabitEthernet0/28 due to MAC address
5254.0039.e564 on VLAN 392

Please fix the issue within your operating system,
and/or declared the Mac address in the OVH manager.

Server sent to Rescue-Pro

Надо починить.

Список MAC можно посмотреть командой: arp -a

Конкретно у меня была проблема с virtio. И пришлось просто новый MAC создать, а старый удалить:





И перезапустить сервер.