Path MTU issue

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Hi All,

I need help to understand below queries regarding attached packet captures. All inputs will be welcomed.

1. What was the MTU size before ICMP error (type3 code4)?
2. Why am I getting ICMP errors from destination server? It should come from any middle router.
3. Is this capture related to proxy? I mean, is there any proxy device in between the source and destination?

Thanks Vaibs