I had to force a restart of the backend pool.
Everyone will have failed over to their backup pool at 03:18 UTC
Pool is back up and working OK, hash rate heading back up to where it was before the restart.
Mine on

What backup pools do people recommend?
I suppose this doesn't make much sense, does it?
stratum+tcp://stratum.kano.is:3333
stratum+tcp://stratum.kano.is:443
stratum+tcp://stratum.kano.is:8080