HDMI boost

Hi
Having an occasional issue. Normally once in a film, often after a long pause, the hdmi signal appears to drop. My projector will start scanning for sources and screen goes black for a few seconds. After that all fine for the rest f the film, It’s quite a long connection: pi3 (libreelec) to matrix to projector using a 5m hdmi cable.

Was thinking that a hdmi config boost might help. Is this a good idea and what would be a safe value to try? Anything else I can try?

Thanks