Alright, server went down again and rebooting didn't help, so I checked the logs and for some reason Redis had shit itself.
"MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error."
Turns out the disk was full and the cron job to clear cached media was broken. Whoops.
All good now!
@nathan I introduced myself to the instance and then it went down. Maybe Redis was scared of me.
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