When you set user 2 to no access to computer B you effectively only tell the program not to show the computer B record in user 2 address book. However, they can still access the remote Host (computer B) if they know access credentials for that Host.
In other words, address book access rights and Host access rights are two different independent things. But you can combine them (see option 2 below).
There are two options to resolve that:
1) Change security settings on the Host. For example, create user accounts on each Host and then if you need to prevent a certain user from accessing a Host just disable their account on that specific Host.
2) Use the "authorization server" role of the RU Server. This is described here (see "Authorization role" section) and we'll also soon update our documentation with detailed instructions on how to set up custom server security as we call it.
With option two properly configured your users will only have to sign in their Viewer to be able to access the Hosts. The advantage of using auth server option is that you can centrally manage Host permissions and change them in one place instead of having to change security permissions on each Host (as is with option 1).
Sorry for the lack of documentation on setting up auth server, it will be available very soon and appear in this chapter. Feel free to ask any questions you might have.
If you can't connect to the 2nd Host regardless of the sleep or login status, then the issue has nothing to do with sleep or being logged in. This looks like a general connection issue. Here are two solution guides that may help you troubleshoot the issue depending on whether it's direct or Internet-ID connection:
Can I give other users logins so that they can log into their PCs?
Unlike LogMeIn Remote Utilities is stand-alone software. There is no web account or a hosted web panel. Instead you install the software on both ends of a connection (on the remote side you can optionally use a run-only Agent) . You can enable a simple single-password access to a remote PC, or create separate users with their own permissions.
Hope that helps. Let me know if you have other questions.
Are you trying to connect from the same network or from different networks? If the former, try to connect to a different network (if you are on Wi Fi, switch to 3G/LTE, or vice versa) and try the same.
Also, could you send a screenshot of your mobile app's server settings window? You can send a screenshot via a private message or to email@example.com