Is there an existing issue for this?

• I have searched the existing issues

Version

equal or higher than v1.18.7 and lower than v1.19.0

What happened?

Hello everyone,
I'm trying to get the vxlan vtep working on a standard ubuntu server. I'm using the example in the official docs.
After the setup, I'm trying to ping a pod inside the cluster from the external vtep server. But it fails. When debugging with tcpdump, I've discovered that I get a zero mac response from cilium:

82:36:4c:98:2e:56 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 10.0.0.32 tell 10.1.1.1, length 28
06:28:12.614902 bc:24:11:90:16:69 > bc:24:11:46:01:6f, ethertype IPv4 (0x0800), length 92: 192.168.0.55.46131 > 192.168.0.52.8472: OTV, flags [I] (0x08), overlay 0, instance 2
00:00:00:00:00:00 > 82:36:4c:98:2e:56, ethertype ARP (0x0806), length 42: Reply 10.0.0.32 is-at 00:00:00:00:00:00, length 28

When trying the same setup with cilium 1.17.13, everything works and I get correct MAC-addresses inside the arp response

82:36:4c:98:2e:56 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 10.0.0.26 tell 10.1.1.1, length 28
06:21:47.340457 bc:24:11:90:16:69 > bc:24:11:46:01:6f, ethertype IPv4 (0x0800), length 92: 192.168.0.55.46131 > 192.168.0.52.8472: OTV, flags [I] (0x08), overlay 0, instance 2
5a:e2:cf:f9:a1:4b > 82:36:4c:98:2e:56, ethertype ARP (0x0806), length 42: Reply 10.0.0.26 is-at 5a:e2:cf:f9:a1:4b, length 28

How can we reproduce the issue?

Install Cilium 1.18.7
Setup VTEP on external linux vm like described in the docs https://docs.cilium.io/en/latest/network/vtep/
Try to ping a pod

Cilium Version

1.18.7

Kernel Version

6.8.0-100-generic

Kubernetes Version

1.35.1

Regression

works fine on 1.17.13

Sysdump

cilium-sysdump-20260220-063821.zip

Relevant log output

Anything else?

No response

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