fixed inconsistency of IP on VR when VR is destroyed and recrea… (#3825)

Author: Pearl1594

server/src/main/java/com/cloud/network/NetworkModelImpl.java

@@ -2298,6 +2298,10 @@ public NicVO getPlaceholderNicForRouter(Network network, Long podId) {
                     } else {
                         ipv6 = _ipv6Dao.findByNetworkIdAndIp(network.getId(), nic.getIPv6Address());
                     }
+
+                    if (vlans.isEmpty()) {
+                        return nic;
+                    }
                     //return nic only when its ip address belong to the pod range (for the Basic zone case)
                     for (Vlan vlan : vlans) {
                         if (ip != null && ip.getVlanId() == vlan.getId()) {