here various experiences and tips are noted which were found by users.

The sound system Pulseaudio (so far only observed on the Raspberry) can run into an error in rare cases. The following message is printed in the console before the QO100 driver terminates:

Assertion 're→data || re→memblock' failed at pulsecore/pstream.c:862, function do_read(). Aborting.

the error has existed for years and unfortunately has not been fixed yet. A resourceful user found the following solution:

in the file: /etc/pulse/daemon.conf you should change:
enable-shm = no

After that the error should not occur anymore. This solution has not been verified by me, because the problem has not occurred here so far.

as with Windows, automatic updates (running in the background) often cause unwanted effects. Especially the high CPU load of auto updates is a problem during a QO100 QSO on a small single board computer.

Automatic updates should therefore be switched off on the QO-100 transceiver computer !

Under Ubuntu based systems this can be done e.g. with the command:
sudo apt remove unattended-upgrades

Concerns all single board computers, but not desktop PCs:

no matter what sound card you use, in setup you always set:
Playback/Recording through the pulseaudio sound server

The adjustment of the sound sources is done with the MIXER.

the install script installs the package mono from the original repository. Unfortunately there are often old versions in there, which have errors. It is highly recommended to install the latest version.

How to do that is described here:

Install Mono