Equipment which provides free wireless internet in Londonderry has been vandalised.
The damage is causing serious problems for businesses and homes across the city, Derry City Council said.
Special hubs for distributing the signal have been damaged, particularly in the Fountain area of the city.
Project officer Louise Breslin said: "The wireless service is a real asset to the community and we have had a lot of feedback from people in the area who are now missing out because some of the hubs are out of action."
Local householders, businesses and visitors can have an hour's free internet access thanks to the equipment.
Ms Breslin added: "This service is essential in maintaining the city's position at the forefront of delivering first rate digital services and therefore it is essential that we keep this equipment in operation."
The equipment was installed as part of the Wireless City Project by Derry City Council. But in recent months many of the nodes (used to distribute the signal) have been disabled or damaged, causing loss of service.
A local community worker has also appealed for an end to the vandalism. Fountain youth club leader Jeanette Warke said: "I would call on all those engaged in this anti-social activity to think about the fact they are disrupting a vital community service, which is used by both the public and businesses alike.
"I will be addressing the issue with some of the young people and trying to raise awareness of how important this equipment is in delivering a free wireless connection.
"Many local people use the service so this type of behaviour is a real detriment to the local community. I would also warn that these are electrical devices which, if tampered with, could be extremely dangerous to anyone interfering with them."