Ongoing issue in Midtown Omaha

We have been having problems the last few nights after 10pm with local channels CBS, NBC, ABC and Fox. I get the error message M.3.1.4 "no signal" on my minibox. All other channels work fine. This has happened before. It stops and starts again. The picture is pixelated and you can't hear or see anything. Why?? We have had several techs out before on this and no one has an answer. Its very frustrating. They say we live in an older neighborhood and that's why. It happens at the same time every night.