Lxc: make host mounted network share available inside unpriviliged container

So I have a unprivileged lxc container on a host system that has a smb network share mounted. I can access files on the network share and although there is a config line like
lxc.mount.entry = /mnt/netshare mnt/netshare none bind,optional,create=dir
present, there is no /mnt/netsher folder inside the container.
The general mounting works great as long as the folder to be mounted is located on a physical drive on the host machine. Net mounted folders on the host seem to never be mountable inside a container.

Btw. a container on a wsl-host behaves the same. The host has a local windows drive mounted as a plan9 file system on /mnt/c but mounting that folder inside a container fails similarly to the smb network share.

How can I fix that?