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Interactive Diagnostic

Wi-Fi & ISP Troubleshooter

Five minutes to figure out whether your slow internet is your ISP, your modem, your router, or your Wi-Fi coverage — and the exact next step to fix it.

Built by Rick · 22 years residential AV installation
Step 1 of 7 · Where you are
Where you are

Tell us about your service.

No personal info — just what you're paying for and who you pay. We use this to tailor the diagnosis to your exact ISP.

Measure

Run a wired speed test first.

Why wired matters: plugging directly into the router with Ethernet removes Wi-Fi from the equation. If wired is also slow, the problem is upstream (your ISP, modem, or the wire to your house). If wired is fast but Wi-Fi is slow, the problem is your router or coverage.

Run the speed test in a new tab:
📡 fast.com (Netflix) 📡 speedtest.net (Ookla)

Plug your laptop directly into your router with an Ethernet cable, run the test, then come back and enter the number below. Don't have Ethernet? Pick the "I can't test wired" option below.

Wi-Fi context

When you ran the Wi-Fi test, how far from the router were you?

Wi-Fi loses ~50% of throughput for every wall it crosses. If you're testing on a TV in the basement against a router in the office upstairs, the test is measuring the worst case, not the router's potential.

Wi-Fi context

What device were you testing on?

Device matters. An iPhone 11 can't pull more than ~400 Mbps even with perfect Wi-Fi 6 — the radio caps out. An iPhone 15 Pro pulls 1.5 Gbps. We adjust the diagnosis accordingly.

Your router

What kind of router do you have?

If it's the box your ISP gave you, we'll factor that in (those routers are usually mediocre and old). If you bought your own mesh, we'll figure out whether you need more nodes or an upgrade.

Your router

A couple last things.

Router age is one of the biggest predictors of bad Wi-Fi. So is total device count — a network designed for 8 devices in 2019 falls apart at 35 devices in 2026.

See your TV plan →

Some product links above are affiliate links — we earn a small commission if you buy through them, at no cost to you. The picks themselves are the ones we'd install in our own homes; commission never influences which model gets the slot. Full disclosure.

Questions people actually ask

Real questions from real readers — and direct answers from 22 years of install experience.

What does upload speed have to do with watching TV?

Watching TV itself uses download bandwidth — but during a game day, multiple devices in the house upload at the same time (Zoom calls, Ring doorbell, FaceTime, security cams, even your phone backing up to iCloud). Cable internet has asymmetric speeds — you might have 800 Mbps down but only 35 Mbps up. When upload gets saturated, EVERYTHING starts buffering including downloads. That's why 'my internet is fast but TV buffers' happens. Fiber is symmetric — no upload bottleneck. The fix on cable: prioritize streams via QoS, or upgrade to fiber if available.

Will my Wi-Fi handle 4 TVs streaming live games at once?

Each HD stream needs about 5 Mbps, each 4K stream about 25 Mbps. So 4 simultaneous 4K games = 100 Mbps inbound. Most home internet handles that. The Wi-Fi side is where it falls apart — a single Wi-Fi 5 router covering 2,500 sqft can't reliably hit 4 TVs in different rooms. Solutions: 1) hardwire each TV with Ethernet (best), 2) Wi-Fi 6 or 7 mesh with a node near each TV cluster, 3) Powerline or MoCA adapters if you can't run cable. We cover specific mesh systems at /wifi/mesh-systems/.

Is my Wi-Fi the problem, my ISP, or the streaming service?

Three-step diagnosis: 1) Speed test wired (Ethernet) into the router — if that's slow, it's your ISP, call them. 2) Speed test on Wi-Fi next to the router — if wired is fast and Wi-Fi is slow, it's your router. 3) Walk to where the buffering happens and test — if Wi-Fi was fast next to the router but slow here, it's coverage, you need a mesh node. 4) If all of the above is fine and one specific app buffers, it's the streaming service (rare, but check downdetector.com).