Live tv delay

My tv boxes are having issues with live tv delays. I watch alot of sports and the tv boxes are 30-45 seconds behind the live tv transmission. The xfinity app I stream on my tablet is ahead of the tv boxes. This issue just stated within the last 6 months. I had a technician come out to the house in the hope he could fix it but he told me there wasn't anything he could do.  I need help Xfinity.