The atmosphere of threats and intimidation that Feyenoord has to deal with is not only annoying for the people in question: it also damages the club's long-term strategy.
For example, an intended investor dropped out.
In September, a group of people, whose identity is unknown, smashed the windows of Mark Koevermans' home.
On Wednesday, the general manager announced that he is stepping down for that reason.
"A possible investor dropped out for that reason, because they were in Mark's garden," Toon van Bodegom, chairman of Feyenoord's supervisory board, told a press conference on Wednesday.
"This not only harms Mark, but also the entire club and policy."
Although Feyenoord cannot confirm a direct connection, it is suspected that the threats stem from dissatisfaction with plans for the construction of the new Feyenoord City stadium.
Feyenoord has been playing in De Kuip since 1937 and some supporters want to stick to that tradition.
According to Feyenoord, the planning for the possible construction of a new stadium will not be jeopardized by the resignation of Koevermans.
"Soon we want to give a press conference on this subject, in which more will become clear," said Van Bodegom.
See also: Feyenoord does not yet see a link between threatening Koevermans and stadium file
Small group of fans have been causing problems for a long time
A small group of people who call themselves Feyenoord fans regularly cause problems.
Last week, the board of the German club Union Berlin was attacked in a Rotterdam restaurant before a Conference League match.
Every European home game of Feyenoord this season resulted in a fine from UEFA for setting off fireworks and throwing objects on the field.
In the past, Feyenoord directors such as Chris Woerts, Onno Jacobs and Marin van Geel also had to deal with threats.
"This kind of problem is not new, we have been dealing with it for twenty years," said Van Bodegom.
"It goes a bit in wave movements, but it just has to stop now. Otherwise we as a club cannot realize our ambitions," said the Feyenoord commissioner.
"We have had a good start to the season in sporting terms. But as a club we also want to step off the field."
Feyenoord is in talks with the police, the government and the KNVB about solving the problems.
"At the moment we can't say anything about it substantively. That could hinder the plans of the other parties. Hopefully more will become clear soon."
See also: General director Koevermans resigns at Feyenoord due to threatsKeywords: