Cause. This issue may occur if the TCP port that is used by the VPN connection is already being used by another program. The VPN connection uses TCP port 1723 to establish a connection. If another program is already using this port, you cannot establish a VPN connection.
The error 633 denotes that the port is already in use or is not configured for Remote Access dial out. You may have to check if the VPN and dial out connection are trying to use the same port that is causing the issue. You may have to check the settings for the modem and change the port for your requirements.
How do I fix Error 633 The modem is already in use?
Fixed: Error 633 The modem (or other communication device) is already in…
- Solution 1: All amateur and irrelevant mobile Internet programs. 2.
- Solution Disable Trusted Network Connection and then re-enable it.
- Solution. Update 3: Adapter drivers from your vendor.
- Solution 4: Then uninstall (and reinstall) your network adapter.
How do I fix Error 633 on my modem?
Fixed: Error Modem 633 (or other nearby device) is already in…
- Solution 1: Install any internet accessories you don’t need. 2.
- Solution Disable the network connection and then re-enable it.
- Solution 3: Update the network adapter driver.
- Solution 4: Uninstall (then reinstall) adapter Interact.
Why do I get VPN error 633 in Windows 10?
In short, VPN error 633 on Windows 10 mostly occurs when VPN connection plug-ins are already in use due to a Windows Designer update or outdated decoder drivers. Today we saw the work of our VPN support engineers who fixed this bug. Easy fix for many VPN 429 errors!!
How do you fix error 633 on Iphone?
Help me please!
- Remedy “Error 633: The modem has already been used or is apparently configured correctly”
- Start the Registry Editor.
- Reserve the TCP port.< /li >
- Update/reinstall your modem drivers.
- Block websites, ISPs, and other features from tracking you.
- Recover individual files quickly.
What is the Error code 633?
Many set-top box users are reporting error 633. This error seems to indicate that your modem is not set up correctly. This error can occur if the communication port used by the modem has been reserved by additional software. Error 633 also occurs when users set up multiple Internet connections.
Which has failed the error code returned on failure is 633?
“Error 633: The modem may already be in use or may not be properly assembled” is not device specific so any model like PC model can be affected. The error message explicitly states the problem is that the modem is not working except for a misconfiguration.

Ermias is a tech writer with a passion for helping people solve Windows problems. He loves to write and share his knowledge with others in the hope that they can benefit from it. He’s been writing about technology and software since he was in college, and has been an avid Microsoft fan ever since he first used Windows 95.