ubuntu 18.04.4 LTS sudo apt-get update

I’m currently running ubuntu 14.04.4 LTS on a Beagle Bone Black (BBB.) I decided to use this distribution on the BBB as I was having issues installing packages(such as minicom) on the supported Debian distribution.

When I try to update ubuntu using the command sudo apt-get update I receive this error.

Err:1 http://repos.rcn-ee.com/ubuntu bionic InRelease   Temporary failure resolving 'repos.rcn-ee.com' 
Err:2 http://ports.ubuntu.com bionic InRelease                           Temporary failure resolving 'ports.ubuntu.com' 
Err:3 http://archive.ubuntu.com/ubuntu precise InRelease                 Temporary failure resolving 'archive.ubuntu.com' 
Err:4 http://ports.ubuntu.com bionic-updates InRelease   Temporary failure resolving 'ports.ubuntu.com' 
Err:5 http://archive.ubuntu.com/ubuntu precise-updates InRelease   Temporary failure resolving 'archive.ubuntu.com' Reading package lists... Done 

NOTE: I have had to remove the rest of the error code due to stackoverflow rules. I will respond with the rest of the error message in the comments below.

• I have updated the /etc/apt/sources.list file.
  What can I do in order to resolve this issue ? Am I having due to the ubuntu version I am currently using ?

>Solution :

For anyone else having this issue.
Checking Network connectivity.