You can check the presence of the back end file(s) and/or the computer that has the back end before doing anything that accesses the back end.  You can use the Dir() function and/or the File System Object to check the presence of files.  And you can use the Windows command Ping to check if the IP address of a computer exists in your network.  You need VBA to do all this.  I believe this site has videos on Dir() and FSO.  I'm not sure if it has anything on using Ping in VBA -- you may need something called Windows Management Instrumentation (WMI) to do that.

If network outages happen "time to time" then you need to do something about that first, because they should be extremely rare or almost nonexistent.  Things like power outages, Internet outages, etc., are understandable, but when they happen they should not affect your database to the point that you have to Ctrl-Alt-Del.  Use a more robust database system such as SQL Server that can handle connections better.  Use a UPS to protect your back end computer from sudden loss of power.  Or design your database for "minimal connection."  E.g. If my PC dies in the middle of composing this message, Richard will not need to Ctrl-Alt-Del, because I don't connect to his database unless I click "Submit," and even so, it will only be a split-second connection.