# Dynamic Path MTU Discovery in Cloudflare One Client

DevFeed: [Dynamic Path MTU Discovery in Cloudflare One Client](<https://devfeed.tech/articles/dynamic-path-mtu-discovery-in-cloudflare-one-client-11354.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2026/03/worth-reading-cloudflare-vpn-dynamic-mtu/>)

Published: 2026-03-11T07:14:00Z

Content type: opinion

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [Cloudflare One](<https://devfeed.tech/topics/cloudflare-one.md>), [Virtual Private Network](<https://devfeed.tech/topics/vpn.md>)

Tags: [cloudflare](<https://devfeed.tech/tags/cloudflare.md>), [cloudflare-one](<https://devfeed.tech/tags/cloudflare-one.md>), [vpn](<https://devfeed.tech/tags/vpn.md>), [worth-reading](<https://devfeed.tech/tags/worth-reading.md>)

## AI overview

This commentary describes how Cloudflare One Client continuously measures end-to-end MTU, adjusts the local tunnel interface MTU, and generates ICMP packet-too-big messages close to the source. The author questions whether this is a novel capability or something other VPN clients have long supported.

## Source excerpt

Here's an interesting tidbit from the what took them so long department: Cloudflare One Client continuously measures end-to-end MTU and adjusts the local tunnel interface MTU size accordingly (warning: there's a fair amount of dubious handwaving over the interesting details), generating ICMP packet-too-big messages as close to the source as possible. I managed to avoid VPN clients most of my life, so I have no idea whether this is a "finally someone figured that out 🎉" moment or a late catch-up to what other VPN clients have been doing for ages. Feedback (in comments or otherwise) would be most welcome!