Networking issues
Troublesome Wi–Fi and shaky Safari
> How do I find shared files?
In Finder, click Network in the sidebar (under Locations) and then double–click on the computer you want to connect to. Once you’ve connected, you should now see the files and folders that have been shared with you. You can add shared folders to the Finder sidebar for quick access in future.
> Why am I getting an invalid security certificate warning?
Certificates are used by secure websites to prove they are who they say they are, but sometimes the certificates aren’t renewed on time or the server settings have changed since your last visit. Sometimes a Mac set to the wrong date or time can generate an error, which creates an invalid security certificate warning.