Single host failes on ansible-playbook

Hello!

Im new to ansible, and have a problem which i just cannot solve:

I use some very simple playbooks to do simple tasks in clasroom management on linux clients (ubuntu).
I.e. i use a playbook for shutting them down. Everything works fine except for one single host.
Whenever I try to use a playbok on a list ho hosts wicht contain this host, I get an error message
for the host about wrong UTF-8 encoding while ansible-playbook is “GATHERING INFORMATION”.

Regular ansible commands are working fine on the host, I can shut it down by executing
ansible -i hosts r110-ws16 -a “shutdown -h now”

but not with
ansible-playbook -i hosts -l r110-ws16 shutdown.yml

which shuts down all other hosts just fine.

I also use a playbook which runs locally (wakeonlan from the server). When this client is powered off,
everything is fine, the host starts up like all the other hosts.
So i figure the problem ist something that is returned from the host while gathering information.

But I have no idea how I can debug this further, any hint would be highly appreciated.

Thank you,

Frank