Once again, 2021 5th International Conference on Communication and Network Technology was held as a fully virtual conference this year. The organizing committees had hoped to meet every participant physically at the conference, but the unstable situation of the covid-19 made it impossible. It is the organizer's responsibility to put the safety and well-being of all the participants top priority. We wish the epidemic will not keep us from meeting with each other at the conference and have face-to-face communications in the near future.
Accepted and registered papers of ICCNT 2021 will be published here: http://www.jocm.us/list-248-1.html