Many LiveATC feeds are provided or hosted by volunteers. Unfortunately, active feeds can go down at any time for reasons beyond our control. Maybe an Internet outage? Equipment issue? No feed is guaranteed to be up 24/7/365.
LiveATC monitors all active feeds and they know that this feed is currently down. Some problems resolve themselves - like internet outages. Sometimes manual intervention is needed to fix problems. Some problems may take longer to fix than others. Some receiver sites are in areas with poor internet and/or power reliability or it's at a site not readily accessible. Hopefully this feed will come back sooner rather than later.