Digi International (DGII) DEFA14AAdditional proxy soliciting materials

Your Vote Counts! Get informed before you vote View the Notice of Proxy Statement, Annual Report,1234567890123456789012345678901234567890, 123456789012345678 9012345678901234567890, 1234567890123456789012345678901234567890, 12345678901234567890123456789012345 67890 online OR you can receive a free paper copy of voting material(s) by requesting prior to <matcutoff>. If you would like to request a copy of the voting material(s), you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control # FLASHID-JOB# Ricky Campana P.O. Box 123456 Suite 500 51 Mercedes Way Edgewood, NY 11717 148,294 322,224 1 OF 2 30# XXXX XXXX XXXX XXXX DIGI INTERNATIONAL INC. 2024 Annual Meeting Vote by January 28, 2024 11:59 PM ET DIGI INTERNATIONAL INC. ATTN: OFFICE OF GENERAL COUNSEL 9350 EXCELSIOR BLVD., SUITE 700 HOPKINS, MN 55343 You invested in DIGI INTERNATIONAL INC. and it's time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy material for the stockholder meeting to be held on January 29, 2024. View the Notice & Proxy Statement, Annual Report online OR you can receive a free paper or email copy of the material(s) by requesting prior to January 15, 2024. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. Vote Virtually at the Meeting* January 29, 2024 2:00 PM CST Virtually at: www.virtualshareholdermeeting.com/DGII2024 *Please check the meeting materials for any special requirements for meeting attendance.

THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming shareholder meeting. Please follow the instructions on the reverse side to vote these important matters. Vote at www.ProxyVote.com Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Sign up for E-delivery”. Voting Items Board Recommends FLASHID-JOB# Control # XXXX XXXX XXXX XXXX THE COMPANY NAME INC. - COMMON ASDFGHJKL 123456789.1234 THE COMPANY NAME INC. - CLASS A 123456789.1234 THE COMPANY NAME INC. - CLASS B 123456789.1234 THE COMPANY NAME INC. - CLASS C 123456789.1234 THE COMPANY NAME INC. - CLASS D 123456789.1234 THE COMPANY NAME INC. - CLASS E 123456789.1234 THE COMPANY NAME INC. - CLASS F 123456789.1234 THE COMPANY NAME INC. - 401 K 123456789.1234 SHARE CLASSES REPRESENTED FOR VOTING This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. 1. Election of Directors Nominees: 1a. Christopher D. Heim For 1b. Sally J. Smith For 2. Company proposal to approve, on a non-binding advisory basis, the compensation paid to named executive officers. For 3. Company proposal to recommend, on a non-binding advisory basis, the frequency of future votes to approve executive officer compensation. Year 4. Company proposal to ratify the appointment of Deloitte & Touche LLP as independent registered public accounting firm of the company for the fiscal year ending September 30, 2024. For NOTE: If any other matters properly come before the annual meeting calling for a vote of stockholders, the shares represented by this proxy will be voted by the persons named herein in accordance with their best judgment.