I have the Arduino IDE installed on an older windows 10 laptop and all works fine. Today I tried using my new Windows 11 laptop and the Tools -> Port option is grayed out. I'm using verion 1.8.19 of the IDE, the most current I believe, and I'm trying to connect to a UNO. I've searched the Arduino forums for like issues but found none.
The Port option from the Device Manager has disappeared. The new procedure, as much as I can divine from YouTube videos, is to go the firewall manager and define an input and output rule, although I'm not certain this is the correct approach, and it didn't resolve the problem. Just to cover all bases, I ordered a new USB AB cable to rule out that possibility.
I'm looking for any hints or approaches to fixing this. Thanks in advance
Have you installed the driver for your specific UNO? Look at the chip next to the USB connector, what does it have printed on it?
On your old laptop, check what device manager says about the board. It might have a CH340 (or other non-16U2) TTL-to-USB converter.
I agree with @missdrew that this has a good chance of being a driver issue.
I have the same issue on an Acer laptop (2019). I have the impression that the problem is in the serial io driver for the laptop (I don't see "ports" in device manager). If I look on the acer site, I only see the windows 10 drivers for this laptop and trying to install the serial io driver it says "not compatible with this platform (I guess windows 11 is meant here)
@reinierdevlaam, which Arduino? Your Arduino might also show under Universal Serial Bus Controllers, but with an exclamation mark indicating a problem.
both ESP8266 and nano...no, nothings shows up when I look in the device manager
Nano clones use often use the CH340 TTL-to-USB converter; ESP boards as well.
So this sounds like you have to install the CH340 driver from CH341SER.ZIP - NanjingQinhengMicroelectronics. I do not know if they are Win11 compatible.
WRONG! You install the driver for the Arduino board, NOT the motherboard driver for your com port.
If the OP provides a link to the Arduino, or the details from the chip next to the USB port, we will have a solution.
this is nothing to do with windows 11, we have 25 laptops here, 10 with windows 11, and all of them work with Arduino, showing the COM port without issue.
I can confirm, these work without issue.
yes, I tried to install the win10 motherboard (Acer) driver. As said, it gives "not compatible with this platform" error, I guess because it is the win10 driver for serial io. There is no win11 serial io driver for this laptop.
As @missdrew said, it has nothing to do with Acer specific drivers. Determine which TTL-to-USB converter is on the board and take it from there.
the NodeMCU I have has the CH340 chip on it, I DID install that driver
Sofar (win10) when I inserted the cable, the COM port popped up, no issue.
Now when I look in the device manager, there is no ports entry. According the Acer website there is a driver for this that somehow fails to install
(I guess because it is win10 driver)
So, one bit of information. In Win 11, the device manager has a VIEW option of "Show Hidden Devices'. How convenient of Microsoft to hide things you might want to see. Once I checked this option, I can see the Ports in the device manager and it shows Arduino Uno (com3). I also installed the CH341 driver from NanjingQinhengMicroelectronics as described in a previous post. The install runs successfully although I can not see any results in the driver description shown under the Port listing in the device manager.
The Device Manager in Win10 says "Standard Serial over Bluetooth link (com3)" , no mention of Arduino. Strange.
Anyway, My issue is resolved, I ran the blink sketch from my Windows 11 laptop and it works. I'm not sure which step solved the issue but I appreciate everyone's indulgence. Thanks
still haven't my solution...
Got the right driver...
If I go to command prompt and type "driverquery >> list.txt"
I get a file with all drivers in windows/system32
in it I find
CH341SER_A64 CH341SER_A64 Kernel 7-12-2018 01:33:15
and several that seem to indicate serial io support
test.h (28.8 KB)
You need to get it out of your head that this is an ACER driver issue. It is NOT, the driver you need to install is for the Arduino, NOT your motherboard.
Please tell us the writting on the chip next to the USB or a direct link to where you bought it from.
If you do not supply this, then I'm out.
it says CH340
as said, I installed the driver
the same board, nodemcu 3.0 with CH340 has been wotking fine on this laptop with win10. since win11 I don't get it to work
well, I found my issue...after I did everything logical I started to look at illogical things.
So the cable that I have been carrying around with my laptop for some time, to connect drives and camera's (and NodeMCUs and arduinos) apparently decided to fail at the same moment I switched to win11 
. I changed the cable for another and everything worked fine again. Then tested that same cable to connect my camera to the laptop...and it works just fine. I test it again with the NodeMCU, it fails. Something odd is going on with that cable, I will dump it.
Reminds me of the time when I still worked for Ericsson and everybody said a serious problem we had to be a SW error and we checked everything 3 times and couldn't find it. At some point I said: "lets just change the hardware". Nobody agreed because all tests showed the HW was working fine but I managed to convince them to at least give it a try. As that HW was hard to get at that time we had to halt the test of another machine to get the right hardware. Et voila, everything worked fine after we replaced the hardware.We inserted the original board again and our SW failed again.The board was send to a special department to check it and nobody could ever find something wrong with it.
Happy you got it working. Good luck on your future projects.