SymptomsVE has been copied manually from one node to another, the copy of migrated VE is left in stopped state on source node. Now it cannot be pinged from source node or any VEs on source node cannot be reached from migrated VE even they are in one subnet.
CauseARP records were not updated in the network
ResolutionDisable offline management for stopped old VE on the source node
vzctl set VEID --offline_management no --save
or destory this VE if you don't need it anymore.