Exhibit 32.1

SECTION 1350 CERTIFICATION

Pursuant to 18 U.S.C. Section 1350, Charles Daniel Vogt, President and Chief Executive Officer of DZS Inc. (the “Company”) and Misty Kawecki, Chief Financial Officer of the Company hereby certify that, to their knowledge:

1.The Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2023 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and

2.The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 9, 2023

/s/ CHARLES DANIEL VOGT

Charles Daniel Vogt

President and Chief Executive Officer

/s/ MISTY KAWECKI

Misty Kawecki

Chief Financial Officer
(Principal Financial and Accounting Officer)