Hi, if a granny annex next to a cotage is let & the tenant allowed to use the owner's broad band can he access the owner's PC/Laptop, interfere with it, read files e.t.c.?
In simple terms, unfortunately, yes. A VLAN will go some way to adding security, but is not impenetrable.
I the owner doesn't have any sharing enabled then I think the tenant won't be able to easily access anything the owner doesn't want him to.
I'd also be concerned about what content the tenant might be downloading from the net?? It's your line so I'd imagine the buck would stop with you if he/she was doing something they shouldn't.
What I would do if I was to make available a connection to someone else 'untrusted' is make a separate AP running something like ipcop that supports forcing a VPN connection service like private internet access and stick it on a different subnet to my personal network. This way it is both isolated from your personal systems and is using a vpn tunnel which theoretically your ISP can't monitor traffic on.
