I am currently experimenting with Syncthing and therefore testing the exact same setup several times. I copy a 18GB folder from one machine to 5 remote devices and log the completion.
This process reliably takes between 1400s and 1550 seconds. But now twice it happened to me that a testrun took much longer (9350s) even though nothing changed in the configuration. I repeated the runs and got the same slow speed. The only way to reset to the previous speed was a restart of the Syncthing daemons on all devices.
Are there any known error, which can produce this sudden reduction in transfer speed?
Edit: I have the audit log running and they grow fairly large to about 400MB in size, but that should not explain the sudden drop.