Not long after I posted last night, it went off permanently - RDY flashing and nothing would make it stay constant. I went to bed. This morning it's fine - at the moment...
---------- Post added at 12:01 ---------- Previous post was at 11:06 ----------
Nah - still up and down

Will have to phone tech support. Last time, it took me the best part of a week to convince them. I'd phone when the RDY light was off, I'd queue, I'd speak to someone, and the RDY light would then be on - tech advises no problem found. In the end, they sent an engineer because I kept calling.
Upstream power level is 61.0 dBmV - probably an issue also