Is It Your ISP or Your Wi-Fi? A 10-Minute Test
Is it your ISP or your Wi-Fi? One wired test settles it in ten minutes. How to read a speed test honestly, what to write down, and what to say on the call.
To answer “is it my ISP or my Wi-Fi?”, use one Ethernet cable. It separates the connection before the router’s radios from everything inside the home: walls, channels, devices and coverage.
If wired performance is slow too, call the ISP after recording the evidence. If wired performance is healthy and only Wi-Fi is poor, an ISP call will not fix it; diagnose the wireless path instead.
Run the 10-minute boundary test#
Bring a laptop with Ethernet (or a USB-C adapter), a known-good cable and the exact plan speed you pay for.
- Test Wi-Fi in the failing room and record download, upload and idle latency.
- Test Wi-Fi beside the router with the same device and server.
- Plug into a router LAN port, turn the laptop’s Wi-Fi off, then run two wired tests about 30 seconds apart.
- Check router/modem status for WAN link speed, reconnects, error logs and signal/line status where available.
| Result | What it means | Best next step |
|---|---|---|
| Wired slow; nearby Wi-Fi similarly slow | Upstream, modem, cable, port or router issue | Document and call ISP |
| Wired healthy; nearby Wi-Fi slow | Channel, router or client issue | Check local radio/configuration |
| Wired and nearby Wi-Fi healthy; far room slow | Coverage/path loss | Move router or add coverage correctly |
| Slow only at night, including wired | ISP contention or household saturation | Repeat timing test |
Remember that a healthy 1 Gbps service often tests around 900–940 Mbps wired because of Ethernet overhead. A 100 Mbps port instead tops out around 94 Mbps. The gigabit speed guide covers every ceiling between the line and phone.
Call with evidence, not a vague complaint#
Write down date, time, plan speed, wired download/upload, latency, modem/ONT status lights and any drops. Repeat at a quiet hour and worst hour. If the problem arrives every evening, see why Wi-Fi gets worse at night before claiming a permanent line fault.
Say: “My plan is / Mbps. At __ on __, wired directly to the router with Wi-Fi off, I measured / Mbps and __ ms latency. I tested twice. Can you check the line, modem/ONT signal, provisioning and errors?” This tells support you isolated the wireless leg and gives them a useful case.
If the wired test is healthy, test the room rather than upgrading the plan. Wi-Fi slow in one room and signal strength versus speed show the local checks; repeated call drops may follow the video-call guide. An extender cannot repair a slow ISP line, but it can help a genuine weak-room path.
Use Range Up to model the coverage case and see the full Wi-Fi extender placement guide for the next decision.
Rule out the simple physical limits#
Before the call, reseat the Ethernet cable and try a known-good one. A damaged cable or a device negotiating at 100 Mbps can look exactly like a provider cap. Check the router’s WAN status rather than only the Wi-Fi app; a modem/ONT reboot can be useful once, but repeated reboots erase the timing pattern support may need.
Do not test while a VPN, cloud backup, console update or multiple streams are consuming the same connection unless that household load is the suspected cause. Test at two times of day. A result that is normal at 10 am and poor at 9 pm is valuable evidence even if it does not prove the provider is intentionally throttling you.
If support resolves the wired issue and the distant room remains slow, treat that as two problems rather than a failed call. The wired baseline is now clean; use it to evaluate the local coverage solution accurately.
Capture the information support can act on.
Use a single, clearly named test log. Include the service tier, device model, connection method, test server, date/time, download, upload, idle latency and latency while a transfer runs. If the modem or ONT exposes downstream/upstream levels, optical status, event logs or link errors, capture those exact readings rather than interpreting them yourself. They give support a starting point without asking you to repeat every basic step.
Make sure the wired test is directly through a router LAN port, not through a powerline adapter, extender, dock with an uncertain link speed or a chain of switches. Disable the device’s Wi-Fi so traffic cannot take an unexpected route. If the router itself is the suspected limit, a direct modem/ONT test may be appropriate only when the provider explicitly supports it and you know how to restore the router connection safely; do not change authentication or fiber equipment on a guess.
The provider can investigate provisioning, line noise, an overloaded segment, modem/ONT health and an outage. It cannot change Wi-Fi channels, move a router or fix a client device inside the home. Presenting the wired result politely makes that boundary clear and reduces the chance that the case ends after a generic reboot instruction.
When the plan is asymmetric, compare the upload result to the advertised upload tier, not download. A 1000/50 service may be working normally at 45 Mbps upstream even though it delivers 900 Mbps downstream. But if either wired side is persistently far below its expected tier in similar conditions, that belongs in the support case.
Frequently asked questions#
How do I know if it is my ISP or Wi-Fi?
Run the same test wired to the router with Wi-Fi disabled. If wired is slow, investigate upstream; if wired is good and Wi-Fi is poor, the issue is local.
Does a wired speed test prove anything?
It bypasses walls, radio interference and the device’s Wi-Fi link. It is the best simple test of the line, modem and router path.
What should I tell my ISP?
Give the plan speed, date/time, two wired results, latency, equipment status and whether the issue changes by hour. Ask them to check provisioning, line/optical signal and errors.
Can an extender fix slow internet?
No. It only repeats local Wi-Fi coverage. It cannot increase a slow wired service, repair a modem or change ISP congestion.