Ryan appeared before a three-man Rugby Football Union disciplinary panel in Bristol, who found his conduct "prejudicial to the interests of the Union and the game, contrary to Rule 5.12."
The ban runs until May 31, with Ryan suspended from the pitch, touchline, technical, tunnel and dressing room areas on match days.
Former England back-row forward Ryan was charged by the RFU following Gloucester's Guinness Premiership defeat against Saracens at Vicarage Road on February 18.
Gloucester lost the game 24-22 in the closing seconds, with Ryan incensed by what he saw as contentious decisions made by Leicestershire official Debney in the build-up to Saracens' last-gasp converted try.
Ryan remonstrated with Debney, a full-time RFU official, after the final whistle.
He has now paid a hefty price though, with the suspension effectively ending his match-day involvement for the rest of Gloucester's Premiership campaign.
Currently third, the west country club are pushing for a title play-off place, with remaining fixtures including games against fellow challengers Leicester and Bristol.
The suspension would also apply to this season's play-off semi-finals and Twickenham final, should Gloucester progress that far.
The RFU panel was chaired by Christopher Quinlan, assisted by John Doubleday and John Brennan.
Ryan, while head coach at Bristol, received a month-long match day ban in October 2001 - he was also fined Â£2,000 - for criticising referee Tim Miller after a league game between Bristol and London Irish.