Hi everybody,
Something similar is happening here, 80 km east of Milan, Until yesterday with a 1 mt dish everything was fine apart from between 7 and 11 pm, when signal quality dropped below the minimum accepted by the receiver for Astra 2f (55% signal quality).
The pattern was everyday as follows , regardless of the weather: medium signal quality (up to 66% ) morning through early afternoon, from then on constant diminishing (63 - 61 -59 % etc.), around 7 pm down below 55% so no more image; back up again to 56-57-59% after 11 pm. For comparison, bbc 1 on astra 1n was and is at 80-81% throughout the day and night.
From yesterday though none of the 2F channels (4/7, ch 4 hd, ch 5, 8901 etc.) is visible anymore, no readings of signal quality from the receiver (this happens when signal quality goes below 51%).