I get that from them too. On Sunday connections where a little stop/start. No weird pauses today, but speeds are lower than normal at about 7Mb down and 3 Mb up, it can stay like that for a couple of days and then goes up to 10/10 or 20/15.
PlusNet Unlimited Fibre an unreliable 3Mb
Three HomeFi 15 to 20Mb.
Gigaclear FTTP 100Mb TBD