F5 (FFIV) 8-K/A Financial Statements and Exhibits

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (No. 333-146195, 333-179794, 333-186765, 333-191773, 333-194620, 333-196405, 333-203494, 333-217436, 333-231799 and 333-231802) of F5 Networks, Inc. of our report dated April 26, 2019 relating to the consolidated financial statements of Nginx, Inc. as of and for the years ended December 31, 2018 and 2017, included in the Current Report on Form 8-K/A of F5 Networks, Inc. filed July 24, 2019.

/s/ Armanino LLP

San Jose, California

July 24, 2019