/usr/lib/x86_64-linux-gnu/libnuclient.so.4 is in libnuclient4 2.4.3-3.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libnuclient.so.4.0.0
/usr/lib/x86_64-linux-gnu/libnuclient.so.4.0.0