Internet slower than your contract? Here is how to prove it
Published 9 November 2026 · SepoooTools blog
You pay every month for "up to 100 Mbit/s". But videos buffer, calls freeze and downloads crawl. When you call the hotline, they say "everything looks fine on our side".
The good news: you don't have to argue with feelings. You can collect numbers. And in Germany, the law even gives you rights if the speed is far too low again and again. This guide shows you the simple path, step by step.
📶 Open the free Speed Test & WiFi Checker
Step 1: Find your real contract speed
Look at your contract, your last invoice or the short info sheet ("Produktinformationsblatt"). In Germany you will usually see three numbers for download and upload:
- Maximal – the best speed you can expect.
- Normalerweise – the speed you should get most of the time.
- Minimal – the lowest speed the provider promises.
Write these numbers down. You will need them for every comparison.
Step 2: Rule out your WiFi first
Most "slow internet" is really slow WiFi. Walls, floors and the neighbours' networks can eat half of your speed before it even reaches your phone. So before you blame the provider, test in two places:
- Next to the router, or better with a LAN cable.
- In the room where it feels slow.
Our speed test compares both results for you and tells you if it's a WiFi problem or a line problem. If the speed is fine next to the router but bad in the bedroom, the provider is not the problem. Then read Is it your WiFi or your internet? for easy fixes.
Step 3: Keep a log for a few days
One test means very little. Speed changes during the day. Evenings between 19 and 23 h are often the slowest, because everyone is streaming. So test:
- in the morning, afternoon and evening,
- on at least three different days,
- always with the same device, and with a cable if you can.
The tool saves every test in a log on your device. You can download it as a CSV file or print it. If you like paper, use our free printable speed log (PDF).
Step 4: Talk to your provider – with numbers
Now you can call or write and say: "Over 4 days I measured 21 times by cable. My average download was 31 Mbit/s. My contract says up to 100." That is much harder to ignore than "it's slow".
The tool makes a ready letter (German or English) with your numbers in it. Ask the provider to check the line and fix it by a clear date. Keep a copy, and write down the ticket number if you call.
Often the fix is simple: a line reset, a new port, a router swap, or a technician visit.
Step 5 (Germany): the official proof
If nothing changes, Germany has an official tool. Under § 57 Abs. 4 TKG you can pay less or cancel your contract early when the speed is far below the contract again and again. But the proof must come from the Bundesnetzagentur's own measurement at breitbandmessung.de. Other speed tests, including ours, do not count as legal proof.
Home internet (DSL, cable, fibre): you use the free Breitbandmessung desktop app on a computer connected with a LAN cable. You do 30 measurements, spread over three different days, within 14 days. The app follows the official rules and gives you a protocol at the end.
Mobile internet: since 20 April 2026 there is also an official app for mobile contracts, called "Breitbandmessung Nachweisverfahren Mobilfunk". It usually needs 30 measurements on five days.
No LAN port on your laptop? A small USB-C to LAN adapter solves that. You also need a LAN cable long enough to reach the router.
When the app shows a shortfall, send the protocol to your provider. Then you can ask for a lower price, or cancel without waiting for the contract to end. Check the details on the Bundesnetzagentur website, or ask the Verbraucherzentrale if you are unsure. This post is not legal advice.
Small things that ruin a test
- Someone else at home is streaming or gaming.
- A phone or PC is doing a big update or cloud backup.
- VPN is switched on.
- An old router or an old LAN cable (Cat 5 is often limited to 100 Mbit/s).
- Testing on a very old phone with a slow WiFi chip.
Helpful things to have
These can make your tests fair and your home internet faster:
- Long LAN cable (Cat 6) – for cable tests and the official measurement
- USB-C to LAN adapter – for laptops without a LAN port
- Mesh WiFi system – if the line is fine but WiFi is weak in other rooms
Als Amazon-Partner verdiene ich an qualifizierten Verkäufen.
FAQ
Is it normal to get less than "up to" speed?
A little less, yes. Getting 80–95% by cable is normal. Getting under half again and again is not normal and worth reporting.
Does a test on WiFi count?
For your own check, yes. For the official German proof on home internet, the measurement must be done with a LAN cable.
Which speed test should I trust?
Use one tool and compare over days. For legal proof in Germany only the Breitbandmessung app counts.
How much can I reduce my bill?
The law says the price is reduced in proportion to the missing speed. The exact amount depends on your case. Ask your provider or the Verbraucherzentrale.
What if the provider ignores me?
Keep all letters and ticket numbers. You can contact the Verbraucherzentrale or the Bundesnetzagentur's consumer service for help.