Event ID 1126 and 1127: Network is unreachable

[guest]

Situation: in your failover cluster, you may receive these event emssage:
Event ID: 1126
Source: ClusSvc
Description:
The interface for cluster node ClusterNode on network 'Public Network' is unreachable by at least one other cluster node attached to the network. The cluster was not able to determine the location of the failure. Look for additional entries in the system event log indicating which other nodes have lost communication with node ClusterNode. If the condition persists, check the cable connecting the node to the network. Next, check for hardware or software errors in the node's network adapter. Finally, check for failures in any other network components to which the node is connected such as hubs, switches, or bridges.

Event Id: 1127
Source: ClusSvc
Description:
The interface for cluster node ClusterNode on network 'Public Network' failed. If the condition persists, check the cable connecting the node to the network. Next, check for hardware or software errors in node's network adapter. Finally, check for failures in any network components to which the node is connected such as hubs, switches, or bridges.

Case 1: Using the Validate a Configuration Wizard to review the network configuration
To use the Validate a Configuration Wizard to review the network configuration:
1. To open the failover cluster snap-in, click Start, click Administrative Tools, and then click Failover Cluster Management. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
2. In the Failover Cluster Management snap-in, in the console tree, make sure Failover Cluster Management is selected. Then under Management, click Validate a Configuration.
3. Follow the instructions in the wizard to specify the cluster you want to test.
4. On the Testing Options page, select Run only tests I select.
5. On the Test Selection page, clear all check boxes except those for the Network tests.
6. Follow the instructions in the wizard to run the tests.
7. On the Summary page, click View Report.
We found the NIC has an issue. Updating the NIC drive fixes the problem.

Case 2: Opening Event Viewer and viewing events related to failover clustering
To open Event Viewer and view events related to failover clustering:
1. If Server Manager is not already open, click Start, click Administrative Tools, and then click Server Manager. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
2. In the console tree, expand Diagnostics, expand Event Viewer, expand Windows Logs, and then click System.
3. To filter the events so that only events with a Source of FailoverClustering are shown, in the Actions pane, click Filter Current Log. On the Filter tab, in the Event sources box, select FailoverClustering. Select other options as appropriate, and then click OK.
4. To sort the displayed events by date and time, in the center pane, click the Date and Time column heading.

We found many event related to virtual network. Restarting the VM fixes the problem.

Case 3: Check the network adapter, cables, and network configuration for the networks that connect the nodes. We found it is the bad cable.

case 4: Check hubs, switches, or bridges in the networks that connect the nodes. The problem is incorrect switch port configuration.