How to Solve Error 633 on Windows 10 PC

  • “Error 633: Modem (or other connection devices) already in use or improperly configured” is a possible error message you may receive when trying to access the Internet, usually over a dial-up connection.
  • This guide explains the causes and solutions to this problem.
  • To fix this error, I recommend that you perform the following steps.
  • There are many reasons that can cause error 633, here are some of the most common ones.
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When you attempt to access the Internet using a dial-up connection, you may receive an error message saying “Error 633: Modem is already in use or improperly configured.” This error message can appear if your modem driver is outdated or incompatible with your operating system. It explains why this error occurs as well as how to fix it. Please follow the steps below to resolve this error.

Perhaps your modem drivers have become outdated or Windows 10 has been updated recently.

The following platform(s) will be supported: Windows 10 Pro Version 20H2 19042.685 (X64) Language: English (United States).

What causes error 633?

The most common causes of error 633 are listed below.

  • Outdated or corrupted system drivers: System drivers are vital for the proper functioning of your computer. If any of these drivers are outdated or corrupted, it can lead to various errors, including error 633.
  • Incompatible modem driver: As I mentioned above, this is one of the most common causes of this error. If the modem driver installed on your system is incompatible with your operating system, you may see this error.
  • Modem already in use: If another program is using your modem, you may see this error. To fix this, you need to close the program that is using the modem and then try to connect to the Internet again.
  • A change in system settings, which usually occurs after an upgrade procedure: A recent change in your system settings can also lead to error 633. These changes usually occur after an upgrade procedure, such as an upgrade from Windows 7 to Windows 10.
  • The same TCP port that the device uses to connect to the Internet is being used by another application or device: If the same TCP port that your device uses to connect to the Internet is being used by another application or device, you may see this error.

Updated: December 2023

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How to repair error 633

Update the network driver

It is important to keep your network drivers up to date in order to maintain an active internet connection. To do so, follow the steps below.

  1. Using the search bar, type “devmgmt.msc” to open the Device Manager.
  2. Add a new section titled “Network adapters”.
  3. Select “Update driver” from the right-click menu of your network adapter.
  4. Your network adapter’s drivers will be automatically updated when you select “Search automatically for updated driver software.”.
  5. To take effect, restart your computer.

You can maintain the internet connection of your computer by following these steps.

As a first step, focus on troubleshooting options. Windows 10 has streamlined the process somewhat.

Reinstall the network driver

  1. Press Windows and type “Device Manager” to open the Device Manager.
  2. Expand the section titled Network Adapters.
  3. Using the right-click menu, select the “Uninstall” option for your network adapter.
  4. Your network adapter driver will be automatically installed when you restart your computer.
  5. Following the instructions on the manufacturer’s website for installing the driver should work if that does not work.

Reserving the TCP port

The TCP port on Windows 10 should be reserved so that you can ensure that all of your data is protected and your computer is secure. In Windows 10, you can make sure that your computer is protected from potential attacks by following these simple steps.

  1. You can find the command prompt by typing “cmd” in the Start menu.
  2. Select “Run as administrator” from the right-click menu of the Command Prompt icon.
  3. Type “netsh int ipv4 set dynamicport tcp start=1025 num=6451” into the Command Prompt window.
  4. You can close the Command Prompt by clicking on the close button.

These steps will help you create a safe environment for your computer and ensure that it is protected from harm.

Use the network adapter troubleshooter

Several built-in troubleshooters are built into Windows 10, which can help users resolve common computer problems. A network adapter troubleshooter on Windows 10 can help you fix problems with your network adapter. Follow these steps to use the network adapter troubleshooter.

  1. Then select Update & Security & Troubleshoot from the Settings app.
  2. The Network Adapter can be found under “Get up and running.”.
  3. The troubleshooter will be run once you click Run.
  4. The troubleshooter can be completed by following the prompts.

Your computer’s network adapter can be troubleshooted to resolve a wide range of common issues such as driver problems, connection problems, and more using the network adapter troubleshooter. The next time you experience network adapter problems, give it a shot and see if it will help you solve them.

We saw today how our VPN Support Engineers fix VPN error 633 in Windows 10 by fixing it using a method that we learned from our VPN Support Engineers.

Perform a system restoration

When your computer becomes unstable or if you’ve installed a program that is causing problems, system restore can help. This process restores your computer to an earlier point. After a restore point is created, any programs installed after it was created will be removed, but you won’t be affected by your personal files.

  1. The Start menu can be accessed by typing “System Restore” into it.
  2. You can create a restore point by selecting “Create a restore point”.
  3. The “System Restore” button will appear. Enter your password or confirm your action if you are prompted.
  4. Then click “Next.” and choose a restore point.
  5. You can then click “Finish” to complete the system restore.
  6. You will be able to roll your system back to any restore point you choose when the recovery process has completed.

RECOMMENATION: Click here for help with Windows errors.

Frequently Asked Questions

There are a few different ways that you can try to fix Error 633 on your Windows 10 PC. You can try reinstalling the network driver, reserving the TCP port, or using the network adapter troubleshooter. If those methods don't work, you can also try performing a system restore.

The error code 633 is a Windows error code that indicates a problem with the network adapter. This can be caused by a variety of issues, including driver problems, connection problems, or software conflicts.

Error 633 can occur for a variety of reasons, including driver problems, connection problems, or software conflicts. If you're seeing this error, it's likely that there is an issue with your network adapter.

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Mark Ginter is a tech blogger with a passion for all things gadgets and gizmos. A self-proclaimed "geek", Mark has been blogging about technology for over 15 years. His blog,, covers a wide range of topics including new product releases, industry news, and tips and tricks for getting the most out of your devices. If you're looking for someone who can keep you up-to-date with all the latest tech news and developments, then be sure to follow him over at Microsoft.