Hi Karthik,
Thanks for your reply. As far as I can see all is set up correctly.
Landscape looks as follows:
Errors I get are only for 3 systems (when I don't fill in login details) - for the other systems/cleints the trusted RFC is being used I think:
RFC for SM_QBWCLNT160_TRUSTED is working
and has correct details:
The Remote Logon button brings me straight into QBW 160. So still a big mystery to me why this is not happening for the Landscape check.