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How to Change COM Port Assigned to Modem on Your Computer

When you connect a modem to your computer using an Ethernet cable, your PC assigns a COM Port number to establish the communication. In many Modem related troubleshooting guides, we provide the step release or change the COM port number assigned to the modem. Instead of repeating the same steps in multiple guides, it is better to write a supporting article for our other network troubleshooting guides. In this tutorial, we give step by step instructions to release or change the COM Port assigned to the modem on your computer.

Steps to Release COM Port Assigned to Modem

  1. Go to Device Manager. To do this follow the steps provided in the link below.

    How to Access Device Manager

  2. Double Click on Modem listed in Device Manager

  3. Click on the Advanced Tab in Modem Properties Window

  4. Click on Advanced Port Settings

  5. Change COM Port Number: Click on the drop-down menu near COM Port Number to do this. If an even number assigned to your modem, the new number must be an even number.

    For example, if the existing COM port number is 2, you can assign even numbers like 4,6, etc. If the existing COM port number is an odd number, you must assign an odd number only. For example, if the existing COM Port number is 1, you can use other odd numbers like 3,5,7, etc.

    It is important, never change an odd number with an even number while changing the COM Port Number.

  6. Restart Computer

After reboot, your computer will assign the new COM Port Number assigned to the modem.

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Just like release COM Port Number, you can reset Winsock on your computer. To perform this follow the steps provided in the link below.
How to Reset Windows Socket on Your Computer

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After releasing and assigning new COM Port Number for your modem, you may be anxious to check the Internet speed you are getting.

  1. Error 633: The Modem is Already in Use or not Configured Properly
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The following link tells how to check it using various tools.
Tools to Check Internet Connection Speed you Are Getting


Amit said…
Worked like charm..
Thanks a lot :)
Admin said…
Thanks for your comment.
Anonymous said…
Thank u so much. It works!!! Amazing great!!!
Unknown said…
A million thanks for the valuable info posted. Error 633 was pain. Changing com ports did the trick. Thanks a ton.

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Alex George
Alex George has Engineering graduation in Computer Science and an MBA in Finance. He had been working as a senior Network Engineer for ten years. His specialization is in Cisco products. Traveling is one of his hobbies and visited various places as part of his onsite work. He visited different places as part of his onsite work like New York, Dubai, London, etc. Right now Alex is a director of one of the leading career development firms in India, which trains students for UPSC, SSC, and PSC examinations. He guides a lot of students to get selection for various prestigious institutions like CBI, Income Tax Department, etc. Alex George is a stock market investor and a very active intraday trader. Engineering Background: He has a B.Tech in Computer Science and Engineering and passed different network and security courses like CCNA, CCNP (Security), CEH, and various Microsoft certifications. Finance Background: Alex has an MBA in Finance. He is an active intraday trader and a Share Market Investor. Webmaster Skills: Alex is a blogger since 2004. He has a working knowledge of HTML, CSS, PHP, and JavaScrip.