Login/password required for Windows 7 public shares

I have set up a small home network with several desktop PCs and a laptop. One of the desktop PCs is a dedicated media centre for TV recordings. They all run on Windows 7. All of them have at least one share which is “public”, meaning that anyone can read from or write into these shares from any of the other computers. Most of these PCs require a login/password after boot, some don’t, e.g. the media centre.

I have now added another desktop PC with Leap 42.1 to this network, as well as a dedicated server, also with Leap 42.1. I have set up Samba and everything work nicely in that respect, except for the following: When I try to access one of the Windows 7 shares from the Leap PC I get always asked for a login/password. That does not really cause a problem with those PCs that have a login and password defined. When I provide those I am in. Nevertheless, the idea of a public share does not make sense in such cases where I have to use a login anyway. And worse, the media centre has no password, hence I cannot provide one. So I remain locked out. However, a Raspi with OpenElec has no problems accessing same share on the media centre. So, the problem seems to be with the Leap computers.

Public shares on the Leap computers are accessible from all other computers. Samba 4.2.4-15.1 is used on the Leaps. There are no firewalls active on the Leaps. The network lies behind a router and is not accessible from the wider internet.

Any comment would be appreciated.