There is no attenuators and the coax is tight on back of the Hub. We have 3x tv boxes so will have to go check them.@Rensin - Power level is a bit low although might be okay however a couple of channels are falling back to QAM32 and QAM16 - they should all be the same, usually QAM64 - which would suggest a noise issue. Have you double checked the coaxial connection and cables on both the router and any TV boxes etc you may have? Do you have any attenuators on the coaxial cable before it goes into the router?
Problem is, it was a bodge install done by NTL 20+ years ago with multi-room, rather than put a central splitter and run to each room upstairs they just kept adding 2 way splitters when needed and from what I remember there is about 8x 2 way splitters around the house plus the surge connectors on each splitter so going to be a pia.
I guess will be easier to disconnect all the 2 way splitters and see if problem is still there.