See this for reference:
#2712
#2128

The issue is that a non-redundant VPC VR with private gateway after restart (with cleanup=true) sometimes screws up the nic sequence and the private/guest network nics and private gateway (static routes) ips end on the same interfaces (such as eth2) with eth3 without any nic configured. The workaround in such a case is to destroy the VPC VR manually, and restart the VPC without cleanup selected.

ISSUE TYPE

• Bug Report

COMPONENT NAME

VR, VPC

CLOUDSTACK VERSION

4.9, 4.10, 4.11