"no route to host" error when installing flannel ipv6 support

[silenceper]

Expected Behavior

normal

Current Behavior

I1108 12:29:37.844796       1 kube.go:120] Waiting 10m0s for node controller to sync
I1108 12:29:37.844836       1 kube.go:401] Starting kube subnet manager
I1108 12:29:37.936503       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:0/120]
I1108 12:29:37.936542       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:100/120]
I1108 12:29:37.936551       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:200/120]
I1108 12:29:37.936557       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:300/120]
I1108 12:29:37.936564       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:400/120]
I1108 12:29:37.936576       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:500/120]
I1108 12:29:37.936583       1 kube.go:429] Creating the node lease for IPv6. This is the n.Spec.PodCIDRs: [fd00::1234:5678:100:600/120]
I1108 12:29:38.845004       1 kube.go:127] Node controller sync successful
I1108 12:29:38.845028       1 main.go:227] Created subnet manager: Kubernetes Subnet Manager - node
I1108 12:29:38.845033       1 main.go:230] Installing signal handlers
I1108 12:29:38.845159       1 main.go:467] Found network config - Backend type: vxlan
I1108 12:29:38.845176       1 match.go:206] Determining IP address of default interface
I1108 12:29:38.845500       1 match.go:262] Using interface with name eth0 and v6 address 2402:4e00:1017:a400:0:9785:c82b:5fb7
I1108 12:29:38.845522       1 match.go:294] Defaulting external v6 address to interface address (2402:4e00:1017:a400:0:9785:c82b:5fb7)
I1108 12:29:38.845577       1 vxlan.go:138] VXLAN config: VNI=1 Port=0 GBP=false Learning=false DirectRouting=false
I1108 12:29:38.845781       1 kube.go:350] Setting NodeNetworkUnavailable
I1108 12:29:38.854471       1 main.go:356] Setting up masking ip6 rules
I1108 12:29:38.942162       1 main.go:370] IPv6: Changing default FORWARD chain policy to ACCEPT
I1108 12:29:38.942246       1 main.go:379] Wrote subnet file to /run/flannel/subnet.env
I1108 12:29:38.942255       1 main.go:383] Running backend.
I1108 12:29:38.942268       1 main.go:404] Waiting for all goroutines to exit
I1108 12:29:38.942290       1 vxlan_network.go:61] watching for new subnet leases
E1108 12:29:38.942533       1 vxlan_network.go:242] failed to add v6 vxlanRoute (fd00::1234:5678:100:100/120 -> fd00::1234:5678:100:100): no route to host
E1108 12:29:38.942641       1 vxlan_network.go:242] failed to add v6 vxlanRoute (fd00::1234:5678:100:200/120 -> fd00::1234:5678:100:200): no route to host
E1108 12:29:38.942733       1 vxlan_network.go:242] failed to add v6 vxlanRoute (fd00::1234:5678:100:300/120 -> fd00::1234:5678:100:300): no route to host
E1108 12:29:38.942811       1 vxlan_network.go:242] failed to add v6 vxlanRoute (fd00::1234:5678:100:400/120 -> fd00::1234:5678:100:400): no route to host
E1108 12:29:38.942897       1 vxlan_network.go:242] failed to add v6 vxlanRoute (fd00::1234:5678:100:500/120 -> fd00::1234:5678:100:500): no route to host
E1108 12:29:39.036118       1 vxlan_network.go:242] failed to add v6 vxlanRoute (fd00::1234:5678:100:600/120 -> fd00::1234:5678:100:600): no route to host
I1108 12:29:39.137158       1 iptables.go:177] bootstrap done
I1108 12:29:39.138077       1 iptables.go:177] bootstrap done

Possible Solution

Steps to Reproduce (for bugs)

1. install flannel

Context

Your Environment

• Flannel version: v0.19.2
• Backend used (e.g. vxlan or udp): vxlan
• Etcd version:
• Kubernetes version (if used): v1.23.13
• Operating System and version: 3.10.0-1160.11.1.el7.x86_64
• Link to your project (optional):

[silenceper]

Upgrading the kernel to version 5.4 solved the problem