Start with measurable causes
Do not infer the source from one speed number. Compare the same device, destination and time under controlled conditions.
CONNECTION DIAGNOSIS
Is Slow Internet Caused by Your Router or ISP?
Compare a wired test at the router with Wi-Fi tests in multiple rooms. Good wired performance with poor Wi-Fi points locally; poor wired results across devices and times are stronger evidence of an ISP or modem issue.
Compare, don’t guess
Connect one capable device by Ethernet. Keep other variables stable, then change one condition at a time.
What can create this pattern
Wi-Fi coverage or interference is the bottleneck
Confirm this possibility with a repeatable comparison before changing equipment or service.
The router cannot handle the current load
Confirm this possibility with a repeatable comparison before changing equipment or service.
The modem or access line is unstable
Confirm this possibility with a repeatable comparison before changing equipment or service.
The provider network is congested
Confirm this possibility with a repeatable comparison before changing equipment or service.
Test it in this order
Connect one capable device by Ethernet
Record the result, keep the test comparable and continue only after this step.
Pause other traffic
Record the result, keep the test comparable and continue only after this step.
Repeat on a second device
Record the result, keep the test comparable and continue only after this step.
Compare results at several times
Record the result, keep the test comparable and continue only after this step.
Use more than download speed
Read throughput together with ping, jitter and packet loss. A browser result describes this device, route and moment; it does not by itself prove an ISP fault.
Continue the diagnosis
speedtest network quality monitor your connectionFrequently asked questions
Is Slow Internet Caused by Your Router or ISP?
Compare a wired test at the router with Wi-Fi tests in multiple rooms. Good wired performance with poor Wi-Fi points locally; poor wired results across devices and times are stronger evidence of an ISP or modem issue.
What should I test first?
Connect one capable device by Ethernet. Use the controlled wired result as the baseline, then measure the Wi-Fi penalty.
Does one test prove the cause?
No. Repeat comparable tests over Ethernet and Wi-Fi, on more than one device and at different times.
MEASURE BEFORE YOU CHANGE
Start connection test →Find where the connection slows down
Save the result, repeat under comparable conditions and use the difference as evidence.