MTU and path MTU test

What is the biggest packet that can reach this host in one piece?

Tested from around the worldPlain English + technicalFree, no sign-up

How to read the results

The health check runs this and 30 more checks on a domain, then ranks what to fix.

Firewalls, switches and Wi-Fi bundled for homes and offices.

Find the path MTU to a host: the largest packet that gets through without fragmenting, to diagnose VPN and tunnel problems.

Every result comes in two styles: plain English for everyone, and the exact technical detail for engineers, with the raw JSON one click away.

If big packets are dropped silently, pages and downloads can hang while small requests work.