It's worth checking the dish/exterior cabling. A fault could have occurred coincidently* around the time of the fibre upgrade. Checking the signal strength would be a good starting point - Settings, satellite signal, more info. In my case (see below) I think what I also did was to unscrew/use one cable at a time checking the signal strength each time which allowed me to identify a faulty cable.
* I had a damaged cable in my setup for a while. A few recordings didn't happen /failed over a period of a few months which I didn't pay much notice to. Due to ongoing building work at one point I disconnected the box for a day or to. When I reconnected I noticed a zero signal although the box seemed fine. Carefully swapping the inputs around/ using just a single cable showed that it was cable/dish related and when I went outside and checked carefully I could see/feel a nick in one of the cables! (It had been damaged by the builders a few months previously - long project! - so it had basically been operating in a single cable mode since then and done a good job tbf!) I got a local guy in and he replaced the cables and it was all was good.
