Thanks. The picture/sound are breaking up.
Looking at other Hi-band services, Freesat UHD/4K demo at 12441 is at 84%. So that Hi-band is OK. But others on the BBC1 South frequency 12168 are much the same.
I'm using a GigaBlue Ultra Unicable SCR-LNB / 24 SCR and Triax 83cm dish.
Is there any simple check of LNB and dish I can do??