Guided diagnosis
Something on your network is slower than it should be.
This works the fault down in order — cheapest test first, one variable at a time — and keeps a record of what has been ruled out. Pick the closest symptom, or describe it in your own words.
Wired — the device is on a cable
most common
Wired is slower than my plan
The cable should be fast and isn't. Start from nothing.
isolated
One device is slow, others are fine
Same network, same router, one machine underperforms.
ceiling
Stuck at about 100 Mbps
Gigabit hardware, a hard ceiling well below it.
unstable
Speed jumps around between tests
Not a clean ceiling — the number won't sit still.
adapter
Slow through a USB adapter
No built-in Ethernet port, using an adapter instead.
quality
Fast, but calls still stutter
Throughput is fine. Something else is wrong.
Wi-Fi — the device is wireless
underdelivering
Far below what it's rated for
The hardware should be much faster than this.
missing
Wi-Fi adapter has disappeared
No wireless interface at all, possibly after an update.
coverage
Fine in one room, bad in another
Speed depends on where the device is.
quality
Wi-Fi is fast but unreliable
Good throughput, yet calls and games still break up.
Latency & upstream — speed is fine, quality isn't
shared load
Breaks up when the house is busy
Fine on my own, unusable when others are online.
jitter
Choppy audio, numbers look fine
Timing problem rather than a speed problem.
one destination
One site or server is slow
Everything else is fine. Just this one.
lookup
Slow to start, then fast
Long pause before anything happens.
Or describe it yourself Describe it in your own words
Start