cloudstack vnet creating error while adding arm devices to cloudstack

[arpanbht]

We are trying to add a nvidia jetson agx thor to our existing cloudstack management server as a kvm host we have setup that machine and did pci passthrough and enabled iommu, the machine is getting added to cloudstack but we are facing these kind of error

net/modifyvlan.sh -v 1644 -p  -b br-1644 -o add ] encountered the error: [Cannot find device "br-1644"/usr/share/cloudstack-common/scripts/vm/network/vnet/modifyvlan.sh: line 37: /proc/sys/net/ipv6/conf/br-1644.1644/disable_ipv6: No such file or directoryCannot find device "br-1644.1644"Failed to create vlan 1644 on pif: br-1644.].
2026-04-10 06:57:19,637 WARN  [resource.wrapper.LibvirtStartCommandWrapper] (AgentRequest-Handler-1:[]) (logid:0d10c5a1) InternalErrorException com.cloud.exception.InternalErrorException: Failed to create vnet 1644: Cannot find device "br-1644"/usr/share/cloudstack-common/scripts/vm/network/vnet/modifyvlan.sh: line 37: /proc/sys/net/ipv6/conf/br-1644.1644/disable_ipv6: No such file or directoryCannot find device "br-1644.1644"Failed to create vlan 1644 on pif: br-1644.
	at com.cloud.hypervisor.kvm.resource.BridgeVifDriver.createVnet(BridgeVifDriver.java:338)
	at com.cloud.hypervisor.kvm.resource.BridgeVifDriver.createVnetBr(BridgeVifDriver.java:320)
	at com.cloud.hypervisor.kvm.resource.BridgeVifDriver.plug(BridgeVifDriver.java:239)
	at com.cloud.hypervisor.kvm.resource.LibvirtComputingResource.createVif(LibvirtComputingResource.java:3861)
	at com.cloud.hypervisor.kvm.resource.LibvirtComputingResource.createVifs(LibvirtComputingResource.java:3438)
	at com.cloud.hypervisor.kvm.resource.wrapper.LibvirtStartCommandWrapper.execute(LibvirtStartCommandWrapper.java:86)
	at com.cloud.hypervisor.kvm.resource.wrapper.LibvirtStartCommandWrapper.execute(LibvirtStartCommandWrapper.java:52)
	at com.cloud.hypervisor.kvm.resource.wrapper.LibvirtRequestWrapper.execute(LibvirtRequestWrapper.java:78)
	at com.cloud.hypervisor.kvm.resource.LibvirtComputingResource.executeRequest(LibvirtComputingResource.java:2280)
	at com.cloud.agent.Agent.processRequest(Agent.java:813)
	at com.cloud.agent.Agent$AgentRequestHandler.doTask(Agent.java:1295)
	at com.cloud.utils.nio.Task.call(Task.java:83)
	at com.cloud.utils.nio.Task.call(Task.java:29)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

2026-04-10 06:57:19,637 INFO  [kvm.storage.LibvirtStorageAdaptor] (AgentRequest-Handler-1:[]) (logid:0d10c5a1) Trying to fetch storage pool a04d1dfc-8cf5-3db0-a2ef-37a92c1bcb9d from libvirt
2026-04-10 06:57:19,696 INFO  [kvm.resource.LibvirtConnection] (AgentRequest-Handler-3:[]) (logid:0d10c5a1) No existing libvirtd connection found. Opening a new one
2026-04-10 06:57:19,697 WARN  [kvm.resource.LibvirtConnection] (AgentRequest-Handler-3:[]) (logid:0d10c5a1) Can not find a connection for Instance i-2-2001-VM. Assuming the default connection.

Let me know if any additional information is needed in order to solve this problem.

Please help. 🥲

[weizhouapache]

the correct command should be like

/usr/share/cloudstack-common/scripts/vm/network/vnet/modifyvlan.sh -v 1921 -p eth1 -b breth1-1921 -o add

is the kvm network label of physical network set correctly ? @arpanbht
if not set, cloudbr1 will be used, which may not exist in your environment.

please check agent.properties on kvm hosts too.