VAG-COM Connection Issues Near Munich?

Hello!

My VAG-COM device (purchased from an online forum shop), which has been working flawlessly for the past 4 years,
suddenly loses connection.
Error message:

Interface not ready.
Interface Status 3, Possible reasons, etc.

I am accessing the serial port COM1.
The VAG-COM test in "Options" reports "Com Port Status OK."

In the loopback test of TestOK.exe (by Andreas St.), the following occurs:
It also doesn't achieve anything.
"Other COM ports 2-4 also don't work (I've never used them before)."
used).
My adapter apparently doesn't have any LEDs.

Either the cable is broken or there's a problem with the diagnostic connector.
Nothing from the vehicle is reaching its destination.

"Someone in the Munich area with a VAG-COM tool to help narrow down..."
"Errors?"

Thank you very much.

Best regards, Klaus.

Volkswagen Golf 3, manufactured in 1998 (engine code AFN).

Hi Klaus,

Selector switch (if present, depending on the construction period) worn out?

Best regards, Rainer.

Hi Rainer!

I'm not exactly sure what the switch is, but...
Older inquiry regarding my order.
"Complete diagnostic adapter kit (RS232)"
Have you responded to me that the KL series does not...?
It has a switch.
This series apparently also doesn't have any LEDs that you can do anything with.
I can see it, or I'm blind.

Best regards, Klaus.

I still have some remaining stock of electronics from the previous version of the KKL.

More details via private message.

Error found, the laptop's serial number is malfunctioning.
I switched to using a USB adapter.
and everything goes back to normal.
Thank you for your support.

Best regards, Klaus.