How to fix modem error 633 after installing the Creators Update

2 minute read

Many users who recently upgraded to the Creators Update have encountered internet connection issues with one of the most common errors reported being modem error 633. This error indicates that your modem is not configured properly.

Error 633 affects all modem model and isn’t connected to any specific device. Here’s how one user describes this issue:

My  zte ac 2766CDMA USB modem not working after i updated to Windows 10 createor update it is giving error 633 please help me it is only Internet connection I have.

Error 633: The modem is already in use or not configured properly

This error may occur if the communication port used by your modem has been reserved by another software program. Error 633 also occurs when users set up multiple internet connections. If error 633 is blocking your Internet connection, follow the troubleshooting steps listed below.

Fix modem error 633

1. Run the built-in troubleshooter

  1. Go to the new Settings page and select the Troubleshoot option in the left-hand pane.
  2. Run both the Internet Connections and Network Adapter Troubleshooters.

2. Update your modem drivers

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Download and install the latest drivers for your modem from the manufacturer’s website.

You can also use the Device Manager to update your drivers:

  1. Right-click Start > open the Device Manager > locate Network Adapters.
  2. Right-click your network adapters > select “Update driver software”. Update both your LAN and WLAN adapters.
  3. Wait until the updates are installed > restart your PC and connect to the Internet.

3. Uninstall and reinstall your modem drivers

If updating your modem’s drivers didn’t eliminate error 633, try uninstalling and then reinstalling them.

  1. Launch the Device Manager and then double-click Network adapters
  2. Locate the network adapter currently used. Right-click it and select Uninstall.
  3. Check the checkbox beside it to enable the “Delete the driver software for this device”option and click OK.
  4. After the network adapter is uninstalled, go to Action. Then, scan for hardware changes. Windows 10 will automatically install the network adapter as well as its drivers.
  5. Restart your PC and connect to the internet.

4. Reserve the TCP port

  1. Press the Windows key +R > type regedit and click OK.
  2. Locate and then click the following registry subkey:
  3. Go to the Edit menu. Select New and then click Multi-String Value.
  4. Name the new multi-string value “ReservedPorts”. Then, double-click it.
  5. In the Value data box, type 1723-1723. Click OK.
  6. Quit Registry Editor and connect to the internet.

If you’ve found other workarounds to fix modem error 633, feel free to list the troubleshooting steps in the comment section below!


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