Shamrock Rovers say that Russian hackers caused a disruption to the club's streaming of the Champions League qualifier against Slovan Bratislava on Wednesday evening.
Supporters of the Premier Division champions who had paid for the streaming service are being offered full refunds after the footage was unavailable to a number of subscribers.
The Hoops lost the first leg tie 2-0, although goalkeeper Alan Mannus kept their hopes alive with an injury time penalty save in the second half.
The second leg takes place in Tallaght next Tuesday.
A statement from the club reads: "Shortly before the start of our Champions League Qualifier against SK Slovan Bratislava last evening, our website came under a sustained Denial of Service (DOS) attack which blocked access to the site and to the live stream of the game.
"The attack, which originated from IP addresses in Russia and the United States, began at 17.25 and prevented new connections to the stream. Anyone already logged in and connected was unaffected.
"Quick and decisive action from Mark Lynch and Bill Gleeson identified the part of the website that was being targeted, which allowed us to shut down the attack and bring the website back online.
"In parallel, our streaming partner, InPlayer, also reacted quickly and moved the hosting of the live feed to one of their platforms. By 17.59, the stream was back and live for all users.
"While the reaction of InPlayer and club volunteers in managing this external attack was exemplary, we do recognise and regret the significant disruption caused to fans who had purchased the stream. As such, we will make a full refund available to any supporter who wishes to avail of it.
"Requests for refund should be addressed to support@inplayer.com before midnight on Friday the 9 th of July 2021.
"Any subscriber to the stream can also watch back the full match recording on the link provided which has been extended to midnight on Friday."
