It's not just CIFS root that needs SMB1. SMB1 has to be used any time you need the POSIX extensions, with Samba at the server side and Linux at the client side

It's not just CIFS root that needs SMB1. SMB1 has to be used any time you need the POSIX extensions, with Samba at the server side and Linux at the client side. I find it comes up reasonably often, because Samba is so configurable. For example remapping user ids, or mapping user-group permission bits; these are hard or impossible to do in NFS, depending on available NFS server version.