Slow internet: a systematic approach before calling your provider
Before you call your internet provider to say the internet "isn't working", it makes sense to go through a few steps that will quickly distinguish a problem on your side from a genuine fault or long-term lower speed on the provider's side. This saves time for both parties and, in the case of a genuine complaint, you will need measured data anyway.
1. Measure speed correctly
The baseline is to measure the connection via a cable directly to the router, not over WiFi - wireless connections almost always skew the result downwards, especially on older routers or at greater distances from them. Perform the test in the speed test at various times of day, as with many technologies speed fluctuates depending on network congestion in the area (aggregation). A single measurement proves nothing - you need multiple samples over time. What the individual figures in the test mean is explained in the article Internet speed: what the numbers in offers mean.
2. Rule out WiFi as the culprit
Before you start addressing speed issues with the provider, verify:
- Is the router within range, or does the signal travel through several walls and floors?
- Are there no interfering neighbour networks on the same channel nearby?
- Has the router been restarted within a reasonable time (not running continuously for months)?
- Is more than one device downloading simultaneously on the network (updates, backups, streaming)?
If the speed via cable is fine but poor over WiFi, the issue is not with the internet provider but in the home network; it is resolved by better router placement, newer equipment or a WiFi extender, not by a complaint.
3. Compare the measured speed with your contract
Check what speed the contract guarantees, not the advertised maximum "up to", but the minimum guaranteed value if stated. A short-term speed drop during peak times may be common with shared technologies. A problem requiring action arises when the deviation from the contracted speed is significant and persists long-term, not just once.
3b. Common causes that are not faults
Before concluding that the fault lies with the provider, consider these possibilities:
- Home network overload - multiple devices downloading simultaneously (system updates, cloud backups, streaming on several TVs at once) will reduce the available speed for each of them.
- Outdated router - older devices may not handle the full speed of the tariff even via cable, especially with newer high-speed connections.
- Peak network load for the provider - with shared technologies (aggregation), speed is usually lowest in the evening when the most users are connected at once; this is an expected, not necessarily faulty state, provided it remains above the guaranteed minimum.
- Issue on the side of a specific web service - slow loading of one particular page or service may be an issue on their side, not with your connection; this can be verified by a speed test to another target.
4. When and how to file a complaint
If the service provided does not comply with the contract over a long period, the Electronic Communications Act (127/2005 Sb.) gives the user the right to complain to the provider and, in case of defective performance, to request an appropriate price reduction. The complaint must be submitted without undue delay, no later than 2 months from the defective provision of the service; after this period expires, the right to complain ceases. In the event of a significant and repeatedly occurring deviation from the agreed conditions, the user has the right under the Act to terminate the contract without penalty.
Before you submit a complaint, prepare:
- A series of measurements from a speed test with date and time, ideally from several days.
- Contract number and precise specification of the service in question.
- Description of how long the problem has lasted and whether it recurs.
If the internet provider rejects your complaint or does not resolve it to your satisfaction, you may submit a complaint (objection) to the Czech Telecommunication Office (ČTÚ), no later than 1 month from the delivery of the complaint resolution decision, or alternatively from the expiry of the deadline for its resolution without result.
5. If the problem persists
If the provided speed consistently fails to match the contract and no solution can be found, it makes sense to compare what else is available at that address. Not every address has only one internet provider to choose from; you can find an overview of all companies registered with the Czech Telecommunication Office (ČTÚ) for your address at katalogisp.cz, and the selection process is described in the article How to choose an internet provider. The actual switch to another provider, including notice periods and rights during the transition, is covered in the article How to change your internet provider.