I had this problem. Repair person came out. Wanted to replace all the RG6 cable under the house, with no capability of fixing up walls he had to bust open.
I declined (loudly) since the thing HAD been working for years just fine with the existing cabling. Suggested that he replace LNB unit, multiswitch, and receiver. Although he was incapable of rational thought to try and determine WHICH of these three could be the problem, I forced him to do it in a rational manner. It turned out that the multiswitch was definitely the problem. Even though it was only a year old, replacing it with a new one immediately fixed that particular problem. Just a thought.
I declined (loudly) since the thing HAD been working for years just fine with the existing cabling. Suggested that he replace LNB unit, multiswitch, and receiver. Although he was incapable of rational thought to try and determine WHICH of these three could be the problem, I forced him to do it in a rational manner. It turned out that the multiswitch was definitely the problem. Even though it was only a year old, replacing it with a new one immediately fixed that particular problem. Just a thought.