NetDiag+
NetDiag+ 1.4.5: the bufferbloat test
The most common complaint a network tool hears is the one a speed test cannot see: the number is fine, and the connection is not.
What it does
For thirty seconds the test loads your line on purpose while pinging two things at once — your router and the internet. Latency that rises at the router means the queue is on your side of the wall: Wi-Fi, or the router's own uplink buffer. Latency that rises only beyond the router means the queue is the ISP's. The result is a grade from A+ to F and a plain verdict naming who is queueing, written so it can go straight into a support ticket as a screenshot. The guide explains how to read it.
Path MTU
Values under 1280 are now flagged as filtered test packets — carrier-grade NAT or a tunnel dropping the probe — rather than reported as a real link limit. 1280 is the minimum IPv6 requires; a "Path MTU" below it is a measurement artefact, and the tool now says so instead of letting you type it into a router.
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