DSL, Cable or Fibre Setup/Switch: Step-by-Step Guide

By: Simon Heinrich – Last updated: 03/2026 

You’ve found your desired tariff and clicked “Order Now”? This guide takes you step by step through the application process—from the availability check via router selection all the way to activation. The process is similar across all established providers.

If you want to dive deeper into home internet or DSL, we recommend our articles  Home Internet in Germany: Get online fast first – optimize later and Optimising your home internet in Germany: DSL vs cable vs fibre.

Auf dieser Seite findest du:

  • Auf dieser Seite findest du:

  • Schritt eins: Verfügbarkeit und Technik prüfen
  • Schritt zwei: Router richtig wählen
  • Schritt drei: Upselling vermeiden
  • Schritt vier: Persönliche Daten und Adresse
  • Schritt fünf: Wechsler‑Vorteil sichern
  • Schritt sechs: Vertrag prüfen und abschicken
  • Schritt sieben: Aktivierung und Test
  • Nach dem Start: Wichtige Weiter‑Schritte

Step one: Check Availability and Technology

When you click “Order Now (Jetzt bestellen)”, the availability check appears first. Enter your exact address (postal code, street, and house number). The provider checks which technology is available at your location and what realistic speeds are possible.

Important: Providers often try to tempt you with the most expensive option, even though your selected tariff is perfectly sufficient. Stick to your choice and carefully double-check what’s selected before clicking “Continue (Weiter).”

Schritt zwei: Router richtig wählen

Next comes the router question: here you can go for the convenient option or save some money if you’re technically savvy. Most providers offer three options:

Option one: Rent a Router

Advantage: Hassle-free, if it breaks, the provider sends a new one immediately. Full support included.
Disadvantage: After 24 months at 5–8 Euro per month, you’ve paid 120–192 Euro.
Recommended for: Those who aren’t technically inclined and value provider support.

Cable Exception: You’ll usually get a router provided at no extra cost. You can use this as long as your contract runs. This basic model is sufficient for the vast majority of apartments.

Option two: Buy Provider Router

Advantage: You own it, no rental costs. Provider support included.
Disadvantage: Higher upfront costs compared to renting (€79-249 one-time), which only pay off after more than two years of use.
Recommended for: If you’re technically savvy and plan to use the router for longer than two years.

Option three: Buy a Used Router

Advantage: Low purchase price, no rental costs.
Disadvantage: Devices have already been used; accessories may be missing, or you might receive defective units.
Recommended for: If you’re technically savvy and don’t need the very latest model.

For DSL:

Fritz!Box 7520,  around 35 Euro on Kleinanzeigen.
As a general rule with Kleinanzeigen: buying in person is always the safest option. If you’re ordering with shipping, check the seller’s ratings carefully.

For Fibre:

Fritz!Box 7520 and Telekom Glasfaser Modem 2 – around €35 each on Kleinanzeigen.

Cable:

Buying used is not recommended.

Why not? The router’s unique identifier (the CMAC address) is permanently linked to the previous owner’s contract in the provider’s system. When you connect the device, the system recognises it as belonging to “Contract X” and since that contract has ended or belongs to someone else, the router simply won’t be activated for your new contract. You can’t ask customer support to reconfigure it either; providers consistently refuse this for leased devices.

Our advice: Don’t cut corners here. Either use the provider’s router or buy a new device from a retailer (ad). A used cable router from Kleinanzeigen will most likely end up as useless e-waste.

Important: The option “I already have a router” is often hidden, with a rental router pre-selected. Look carefully!

Step three: Avoid Add-On Offers

After the router selection, add-on offers appear and if you’re not paying attention, you can easily end up paying 15–30 Euro more per month.

Commonly offered:

  • Streaming: Netflix, Disney+ (€10–15/month)
  • Antivirus software: Often overpriced (€5/month)
  • Other: Music subscriptions, cloud storage
  • Landline flat rate: Usually included in the contract at no extra cost
  • Mobile flat rate: Only if needed, comes at an extra charge (€5–15)
  • International flat rate: Check if necessary, calls to landline can be pretty cheap for some countries
  • Professional setup: Usually very expensive and rarely necessary

Tip: Go through every single checkbox – providers often pre-tick them by default!

Step four: Personal Details and Address

Now you’ll enter your contact information:

  • Address: In a multi-unit building, specify your exact location if prompted, e.g. “2nd floor, apartment 3 right.” Street names often need to be abbreviated, for example, instead of “Hauptstraße” you’d write “Hauptstr.” If you’re unsure, just type the first few letters (e.g. “Haupts”) and the system will usually suggest completions automatically.
  • Tip: Even if it says “a technician will visit” – for cable, DSL and fibre, activation is usually done remotely!
  • IBAN: For monthly direct debit (SEPA)
  • Preferred start date: Enter the date on which you’d like your connection activated. Not all providers offer this option. We recommend only signing up with providers that let you choose the date yourself, either by entering a preferred date or by requesting a switch that takes effect on the exact day your old contract ends.
  • Customer portal login: Choose a username and password. Keep these safe, you’ll need them later for billing and account management.

Fill in all mandatory fields completely and leave optional fields blank.

Step five: Make the Most of Switching Benefits

If you’re switching providers, always enter your old phone number – even if you never actually used it – and indicate that you’re an existing customer switching providers. Switching tariffs are often cheaper than new connection rates. You’ll also need to provide the end date of your current contract; your new provider will then handle the cancellation on your behalf and ensure there’s no gap in service. That said, you should initiate a switch at least four weeks in advance, so make sure you plan ahead.

Step six: Review and Submit Your Contract

Before submitting:

  • Double-check all details (name, address, IBAN, router, add-ons)
  • Note down or screenshot the contract details: start date, monthly price, minimum contract term
  • Download the terms and conditions

After submitting:

  • Confirmation email and application number (save it – it should also include a summary of your contract details)
  • Credit check via Schufa (automatically)
  • Contract confirmation with further information on next steps

If you’ve ordered a router, it will be shipped to your address around 1–2 weeks before your contract start date. If you’re switching providers due to a move, it’s worth having the router sent to your old address instead. This can usually be specified during the application process.

Step seven: Activation and Testing

On the day of activation, your connection is usually switched on remotely in the early morning hours – often between 4 and 6 a.m. When you wake up, the first thing to do is check your router: turn it on and make sure all the relevant LEDs are showing as expected.

Once the connection is live, run a speed test straight away. Then set up the router app, give your Wi-Fi network a unique name and a secure password, and check that streaming, video calls, and work-from-home applications are all running smoothly. If you notice any issues, keeping a documented record of multiple test results throughout the day can be helpful if you need to raise a complaint with the provider or, if necessary, assert your rights under telecommunications law.

Once everything is up and running, don’t lose track of your contract. Many internet contracts become significantly more expensive after the initial minimum term, typically after 24 months, as introductory discounts expire. It’s worth setting a calendar reminder around 22 months after your start date, so you can take your time to compare options and switch again if it makes sense, benefiting from new customer rates rather than quietly paying the higher standard price. That way you stay in control of your costs and keep getting the best value for money – with no unpleasant surprises on your bill.