I've got a problem here and I didn't even know how wide spread it was. One of my staff members gets logged out in less than one minute, and it keeps him from doing the work I've assigned to him. I thought it might be because of his ISP or browser but that doesn't seem to be the case. More and more of my members are reporting that they get logged out frequently, usually within less than 5 to 10 minutes of active browsing. I've suggested they tick the "keep me logged in" box but this does nothing so help the problem. Recently even I've begun to experience this issue, at least for me it's usually every 15-20 minutes. Then there are some users that never get forced logged out. This is a strange problem, I thought it may even have something to do with DNS and my nameservers so I switched them around and nothing. This problem didn't exist before we switched from IPB so I doubt it's server-end although I can't even be sure if it might be something in xenForo. I'm really at a loss here.
I've been thinking about this for a while. It could take some effort on your part to get more information.. but if you wanted to have the people with problems help you out:
You could sign up for a XenForo demo, have those people register / post / test to see if it is a problem there. Or even on another xf forum.
Wish I could suggest something else that would not involve getting help from your members with problems, because that is incredibly difficult and inconvenient to do.