You will be logged out if your IP address changes mid-session or if you login from another browser/computer. If you are using a VPN service, it is not uncommon for VPN providers to change your IP address in short intervals, causing you to disconnect.
If you continue to be logged out unexpectedly, create a support ticket and set the ticket type to 'Log-in Issue'.
If you suspect someone has compromised your account, check your login history for unrecognized logins to your account. If you do notice unusual activity, create a support ticket and mention 'Compromise/Breach' in the Subject field and a support agent will assist you as soon as possible.