And just that I published this question, I found an old thread with the solution.
In the readme the following is linked:
https://www.mobileread.com/forums/sho...6&postcount=13
Which states "Except, well, with the IP that matches your config. ...(i.e., set the IP to 192.168.15.201 instead)."
That confused me as I thought this means I got to use 192.168.15.201 but I finally saw the link to the original thread of that in the top corner which leads to here:
https://www.mobileread.com/forums/sh...d.php?t=201572
where there is a good summary in the spoiler of the first post
there its stated to use 192.168.15.1
so I did and finally it worked.
I am now able to ssh into the kind but do I have to do the
# ifconfig usb0 192.168.15.201
and
# ifconfig usb0 down
part too? the readme is not so clear about what that does or if its just for linux (which is my guess that its the mount part or so for linux)