Assuming that your disks, DB, CPUs and RAM were all ok, maybe you did not set up PiWik's jobs that are supposed to aggregate the metrics every XX hours/days...

Assuming that your disks, DB, CPUs and RAM were all ok, maybe you did not set up PiWik's jobs that are supposed to aggregate the metrics every XX hours/days... ? https://matomo.org/docs/setup-auto-archiving/ https://matomo.org/docs/setup-auto-archiving/