My Cloud is extremely slow when accessing via file explorer

I use a My Cloud at the office (15+ computers). We access it via file explorer on our PCs. For years, it has always been fast but over the last week one of our PCs is having a hard time getting the files to load. It will take 30-60 seconds to load the folders. If the drive is reset, it will be faster for a day and then go back to being slow again. I am not extremely IT savvy but I am wondering if I am missing something basic. To my knowledge nothing has changed in the last week that would create this slow down on just one of our PCs. Any solutions?