How to Correct error 633 ‘The port is already in use’ in Huawei Dongle and ZTE Modem? Yesterday, I had written about “How to solve error 631 in Huawei modem and ZTE dongle?“. Today, I am going to write about Error 633 which you might have already occurred in Huawei or ZTE modem. If you’re using a USB modem with a Windows computer and get error message 633 ‘The port is already in use’ when trying to connect to the internet.
Error 633 ‘The port is already in use’ might due to the following reasons :
- The computer wasn’t shut down properly while still connected to the internet
- A software conflict with the USB modem
- An issue with the way Windows is managing the communication ports on your computer
How to fix error 633 ‘The port is already in use’ in Huawei or ZTE or any another dongle ?
The possible solution for above mentioned error 633 “The port is already in use” is the following :
- Deleting non-present modems
- Changing the communication ports
- Disabling startup items
DELETING NON-PRESENT MODEMS :
1. Remove all USB devices except the modem from the USB port of computer.
2. Now go to the Start menu and click on Control Panel. Choose Phone and Modem Options.

3. Here, from the Modems tab, remove all Not present modems, which is not Attached to any COM port.

4. Now restart the computer with the modem plugged in and try connecting to the internet again. If these steps don’t fix the issue, try changing the communication ports.
CHANGING THE COMMUNICATION PORTS :
1. Go to My Computer / Computer and right click on it and select “manage“.
2. Expand Modems, and right click on the connected Modem and then click on Properties.

3. Click on the Advanced tab at the top of the properties window and then click the Advanced Port Settings button.

4. The advanced settings window will open. Click the COM Port Number drop down box at the bottom of the screen, and choose a new COM port. Make sure it’s not already in use and click OK.

Now restart your and error should be fixed. If not then proceed with next steps.
DISABLING STARTUP ITEMS :
1. Go to the Start Menu then click on RUN, type msconfig and lick on OK.

2. Click the Startup tab in the System Configuration window.

3. Click Disable All and then Apply.

4. All boxes in the Startup Items should now be unticked. Click OK.

5. A window will pop up asking to restart the computer. Click Restart and the computer will restart without running the startup applications.

Very valuable guidelines explained in easy steps. Thank you.
Welcome.
Sir I followed these step but my laptop is lock and unable to login only lock screen show
RESOLVED – If you encounter 633 connection error after Windows 10 SP update, please note the following link
https://answers.microsoft.com/en-us/windows/forum/windows_10-networking/dial-up-error-633-winstall-of-build-15063/2c5b280e-e246-4105-b8e6-58e413d2668e?tm=1491426971838
This fix the error
Hakki’s contribution did for me, problem since last big update.