The suspension was handed down by the Canadian Centre for Ethics in Sport on Sept. 8.
While under suspension, Zettler is ineligible to participate in any capacity with any sport that complies with the Canadian Anti-Doping Program, a set of rules that governs doping control in Canada.
A former wide receiver with the Waterloo Warriors, Zettler was at the centre of a doping scandal at the school four years ago.
Waterloo suspended its entire football program in 2010 after urine tests conducted revealed several players had committed anti-doping violations.
In 2013, Zettler was convicted on three counts of possession and possession for the purpose of trafficking in anabolic steroids.