After being named president and CEO of F5 Networks in April, Manny Rivelo has resigned from those posts “for matters regarding personal conduct,” the company announced Monday afternoon.

F5 says that Rivelo’s resignation isn’t related to the company’s operations or financials. Rivelo also resigned from F5’s board of directors.

Rivelo had replaced John McAdam, who joined F5 as CEO 15 years ago and retired in July. McAdam is now interim CEO and president until the company finds a permanent successor. He's stepped down as the chairman of F5’s board of directors, although he’ll still have a seat on the board.

Rivelo was F5’s executive vice president of strategic solutions prior to taking over for McAdam. He joined F5 four years ago from Cisco, where he was senior vice president of engineering systems and operations.

F5 has been under duress this year, with analysts questioning whether it's an acquisition target. That speculation ramped up at the first of this month when the applications delivery controller (ADC) and security vendor’s shares hit a 52-week low.

In October, Rivelo presided over F5’s fourth-quarter earnings, which included a smaller-than-expected first-quarter forecast and sent the company's stock down 9 percent after-hours.

Alan Higginson, who currently serves as F5’s lead independent director, has been named non-executive chairman of the board.

In the press release, Higginson said that the change in management is “unexpected” but is “strictly related to personal conduct matters,” without elaborating.

F5's shares were down 1.25 percent after the market closed on Monday.