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Knowledge document #45

Internet access over a different modem / router is slow

The internet connection on computers, smartphones, and other devices connected to the FRITZ!Box is very slow. As a result, web pages load slowly, it takes a long time to download files, and video streams are not played correctly or are interrupted, for example.

In this case, the FRITZ!Box connects to the internet over a DSL, fiber optic, or cable modem, or uses an existing internet connection in the network.

Simply proceed as described below. After each measure, check whether the problem is solved.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Box.

1 Restarting the modem / router

The modem or upstream router may be malfunctioning, for example due to an error that occurs occasionally:

  1. Restart the modem or router by unplugging it briefly.

    Note:It may take several minutes for the modem or router to restart. You cannot access the internet while it is restarting.

2 Setting up WAN port for gigabit LAN

The following step is only necessary if your internet service provider guaranteed you speeds of over 100 Mbit/s:

  1. Click "Home Network" in the FRITZ!Box user interface.
  2. Click "Network" in the "Home Network" menu.
  3. Click on the "Network Settings" tab.
  4. Enable "Power Mode" (1 Gbit/s) for the "WAN / LAN 5" port.
  5. Click "Apply" to save the settings.

3 Setting the speed of your internet connection in the FRITZ!Box

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "Account Information" in the "Internet" menu.
  3. In the "Downstream" and "Upstream" fields in the section "Connection Settings", enter the speeds of the internet connection for receiving (download) and sending (upload) data in Mbit/s. If the fields are not displayed, the speeds of the internet connection are determined automatically. In this case you cannot adjust them.
  4. Click "Apply" to save the settings.
  5. Test whether the internet connection is fast enough now.
  6. If internet access is still much too slow:
      1. Slightly reduce the upstream value, for example by 1 Mbit/s.
      2. Test whether the internet connection is fast enough now.
      3. Repeat these steps several times and use the setting that gives you the best speed.

4 Checking the speed of LAN connections

The following step is only necessary if your internet service provider guaranteed you speeds of over 100 Mbit/s:

  1. Click "Home Network" in the FRITZ!Box user interface.
  2. Click "Mesh" in the "Home Network" menu.
  3. In the "Mesh Overview", check the connection speed shown for the devices connected to the FRITZ!Box via network cable.
  4. If LAN connections are established with no more than 100 Mbit/s although the devices support gigabit LAN, follow the steps in our guide Transfer rate of LAN connections is only 100 Mbit/s.

5 Deactivating bandwidth reservation

The maximum throughput cannot be achieved on internet connections with speeds of 1 Gbit/s and more if bandwidth reservation is enabled for the home network:

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "Filter" in the "Internet" menu.
  3. Click on the "Prioritization" tab.
  4. Disable the option "Reserve bandwidth for the home network".
  5. Click "Apply" to save the settings.

6 Optimizing Wi-Fi connections

The following step is only necessary if Wi-Fi connections to the FRITZ!Box or a Mesh Repeater are significantly lower than the Wi-Fi speed that can be achieved with the FRITZ!Box:

  1. Follow the steps in our guide Slow Wi-Fi connection.

7 Adjusting the Windows network settings

In order for a computer to access the internet, all web requests from the computer must be forwarded to the FRITZ!Box. If the computer automatically obtains its IP settings from the FRITZ!Box via DHCP, it also automatically receives a default gateway (IP address of the FRITZ!Box).

Configuring multiple default gateways is not allowed and causes errors. Therefore, make sure that only one single default gateway is configured on the computer:

Note:Note for network experts: Default gateways required for routing to another IP network can be replaced by a static route. Refer to the Windows help for information on setting up static routes.

  1. Press the keyboard shortcut Windows key + R.
  2. Enter cmd in the "Open" field and click "OK".
  3. Enter route print in the command prompt window and press Enter.
  4. If you see several entries in the table with 0.0.0.0, then there is more than one default gateway:

    Windows 11

    1. Click (Start) and then (Settings) in the Windows task bar.
    2. Click "Network & Internet" in the "Settings" menu.
    3. Click "Advanced network settings".
    4. Click "More network adapter options" in the section "Related settings".
    5. Right-click the network adapter that is not connected with the FRITZ!Box.
    6. Click "Properties".
    7. Select "Internet Protocol Version 4 (TCP/IPv4)".
    8. Click "Properties".
    9. If a default gateway was entered, remove it.
    10. Click "OK" to save the settings.

    Windows 10

    1. Click (Start) and then (Settings) in the Windows task bar.
    2. Click "Network & Internet" in the "Settings" menu.
    3. Click "Change adapter options" in the section "Advanced network settings".
    4. Click the arrow next to the (Change view) button in the menu bar and select "Details".
    5. Right-click the connection for a network adapter that is not connected to the FRITZ!Box. The name of the adapter is listed under "Device Name".
    6. Click "Properties".
    7. Select "Internet Protocol Version 4 (TCP/IPv4)".
    8. Click "Properties".
    9. If a default gateway was entered, remove it.
    10. Click "OK" to save the settings.
  5. Repeat these steps for all network adapters that are not connected to the FRITZ!Box.

8 Checking internet applications

VPN connections and applications that monitor or regulate internet access, such as firewalls, virus scanners, parental controls filters, or software that prioritizes individual internet applications, can reduce the speed of the internet connection.

  1. Clear any existing VPN connections and disable all other internet applications for testing purposes.
  2. Test the speed of the internet connection, for example download a large file.
  3. If the internet connection is fast enough now, configure the other applications so that they do not limit the speed of the internet connection. Refer to the manufacturer of the application for information on how to set it up, for example consult the manual.

Now the FRITZ!Box and the devices connected to it establish the fastest possible internet connection. If internet access continues to be slow, your internet service provider may be throttling the speed, experiencing technical difficulties, or there may be an error with the upstream modem or router.

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