How to fix error error-cluster-last-internal-network in Windows 11

Solution Steps

1. 1 Open Failover Cluster Manager: Press Windows key + R, type 'cluadmin.msc', and press Enter. Click Yes if prompted. This is the main tool for managing cluster networks.
2. 2 In the left pane, click on 'Networks'. Review the list of networks. Identify which networks are marked as 'Internal' (usually used for cluster communication). If there is only one internal network, you cannot take it offline. To proceed, you must add another network to serve as the internal network.
3. 3 To add a new internal network, you need to configure a network adapter on all cluster nodes that will be dedicated to cluster communication. On each node, open Network Connections (Win+R, type 'ncpa.cpl', press Enter). Right-click the adapter you want to use, select 'Properties', then 'Internet Protocol Version 4 (TCP/IPv4)'. Assign a static IP address on a separate subnet from your client network. Repeat on all nodes.
4. 4 After configuring the adapters, go back to Failover Cluster Manager. Right-click on 'Networks' and select 'Add Network'. Follow the wizard to add the new network. Ensure that you mark it as 'Allow cluster network communication on this network' and optionally 'Allow clients to connect through this network' if needed.
5. 5 Once the new internal network is added, you can safely take the old internal network offline. Right-click the old network and select 'Take Offline'. The cluster will now use the new network for heartbeat communication.