COM3: Port occupied or does not exist

Hi all, trying to read data from the batteries of a solar panel installation with 4 different apps (2 provider specific + Putty + HyperTerminal) and a USB/RJ45 data cable I have the same problem in all 4 apps: COM3 (or 4) won't connect.

The message is: "COM3: Port does not exist or is occupied" or "COM3: a device connected to the system is not functioning properly."
Adjusting Baud rate to 115200 does not help.

Looking into Device Manager/Details reads: "UCSI PPM failed to complete UCSI command in a timely manner. Please contact UCSI device or system manufacturer to investigate. (Command:GetCapability)." I have no clue what that means or what to do.

In the Device Manager there is no anomaly, no exclamation mark on any of the USB devices or COM ports that work fine when connectiong any USB device. I have also installed a CH341ser driver (because that's the port's name in the Device Manager) but that didn't change anything. But uninstalling it keeps the port from being listed at all. So I reinstalled it. Uninstalling it, then restart the laptop hoping Windows will reinstall its driver doesn't work.

I'm running W11 26H2 on a HP Elitebook 745 G5 (initially on W10, but several previous W11 versions have worked fine so far). Trying to connect with a different HP laptop running on W11 25H2 gives the same negative results on all 4 apps.
Worse: in the past I was able to read data on these batteries with HyperTerminal - not anymore, even though the provider sent me the latest version + a specific driver for the USB/RJ45 data cable which I installed. Restarting the laptop after driver installation has no effect.

I have spent a lot of time looking for a solution, contacted HP support to no avail, and I don't know anymore what to try. I could try MS support, maybe ...
Maybe some of you know that domain and can help ...?
Thanks very much in advance for your tips - and your time.

hader said:

You know that Window 11 26H2 is still in it's development stage? Maybe some functions are not finished yet. 24H2 and 25H2 are released official products. They work but 26H2 not at this moment. I think you have to wait until autumn for the official release of 26H2. The chance is very high that that release version functions correctly. You can talk to MS about this but I think they will give you the same advise. As someone called it; "it's done when it's done." MS will not support releases that are still under development.....

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True, but as I wrote: same pb with different laptop running on official 25H2 release.

Can you provide any information as to the battery plant? Make, model etc. What does the battery plant's User Manual say about the port in question?

telepro21 said:

Can you provide any information as to the battery plant? Make, model etc. What does the battery plant's User Manual say about the port in question?

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Pytes has 2 home apps for their batteries. The battery plant's User Manual says nothing about the port in question. You're supposed to simply connect and read the data. Which I did - in the past.

hader said:

Yes I know but you stated: "I'm running W11 26H2 on a HP Elitebook 745 G5 (initially on W10, but several previous W11 versions have worked fine so far). Trying to connect with a different HP laptop running on W11 25H2 gives the same negative results on all 4 apps."

Are you now saying that Windows 11 25H2 also can't reach an other Windows 11 25H2 machine?
Maybe you can be more spesific?

With what system and version does it not work connected to which system and version? (Make a matrix with system to system and version and just at the end FAIL or PASS.) Maybe I understood your question incorrectly.

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I am not trying to connect to an other laptop. I am trying to connect 2 different laptops to a Pytes battery in order to read its data.

Have you tried different USB Connecting cords?

TraderGary said:

Have you tried different USB Connecting cords?

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Thanks Gary, no, because this one works. Not now on these 2 laptops, but in the past on one of them, and last week on a MacBook Pro.