Thank you @mawinter69 @poddingue for your prompt responses and willingness to assist, much appreciated!
Although, the initial suggestions didn’t resolve my issue, I continued my investigation. After exploring and digging JENKINS_HOME i.e. /var/jenkins_home, I noticed the init.groovy.d directory, I discovered groovy script named base.groovy that was resetting the Jenkins Location URL to localhost:8080. By modifying this script, I was able to set the correct base URL, and now everything works as expected.
Thank you all for your support!