Welcome to the Community. I did a bit of reseach on this issue and found these suggested steps.
1) Check to see if the device is hidden. For this, click show hidden devices under View, then expand all the nodes under device manager. Uninstall any entries which appear grayed out, then restart. Then try plugging your external device to the computer and see if it works.
2) Make sure that in the BIOS the ports are enabled and set to 'auto'.
If the Ports(COM & LPT) does not show up even after going through the above steps,You may need to add the ports manually. Go into "add/remove hardware", then choose the option that says "let me choose what hardware to install", then go to "choose hardware from a list". Scroll down the list and find the "com ports". Then choose to "add com port". Do the same for lpt.
Hope this helps,
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