Problemns in Ubuntu 18.04 with boot in clients

Hello list:
I'm trying to create 2 LTSP servers to compare in performance, one in
Ubuntu 18.04 and the other in Debian 9.
In Ubuntu 18.04 the image was created without problems and in fat client
mode. When any of the clients starts, the process stops in the section of
defining the default keyboard in the console.
In Debian 9 everything works well, that is, this problem does not occur.
As a test I created a 3rd server in Ubuntu 16.04 and it works fine until
the version of the kernel 4.4.0-137, since to keep updating the same fault
appeared in Ubuntu 18.04.
In the link [
https://drive.google.com/open?id=1ThkZ4LvMO0t7N7oDLUy4WcYHd2k-vyyA] I have
the screenshots where evidence of the error at the beginning of the client
and of the versions of the packages in the 2 scenarios that are left I'm
trying.

regards

Note: I am Spanish speaking and this message has been generated by Google
Translate ;)

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