[Bug] - Repeated ndisc_router_discovery failed messages in the journal when using systemd-networkd

[derlopes-amzn]

Describe the bug
I am seeing the exact same issues as described in bottlerocket-os/bottlerocket#3411

We are using EKS 1.32 with AL2023 node version 1.32.3-20250627. This is not present on our AL2 nodegroups.

To Reproduce
Steps to reproduce the behavior:

1. Deploy nodegroup with eks.NodegroupAmiType.AL2023_X86_64_STANDARD AMI
2. SSM into a host
3. Run dmesg -w
4. Observe ICMPv6: RA: ndisc_router_discovery failed to add default route errors

Expected behavior
No errors related to ndisc_router_discovery failed

Additional context

The suggested workarounds listed in bottlerocket-os/bottlerocket#3411 also work for this error. echo 0 | sudo tee /proc/sys/net/ipv6/conf/ens5/accept_ra or echo 1 | sudo tee /proc/sys/net/ipv6/conf/ens5/accept_ra stops the errors entirely.

[xcawolfe-amzn]

Hi @derlopes-amzn, we are taking a look and will get back to you on this