Yes, it's a bug in the firmware. The function "
Save Config" works just one time after a reboot/power-cycle.
You can see this when clicking "
Save Config": a message "
Saving Configuration to FLASH" appears for a very short moment followed by "
Save the configuration successfully".
Next time you click on "
Save Config" only the latter message appears, but nothing is saved into flash memory. So, after a power failure all changes are lost even if you saved them.
Work-around until fixed: Do a prophylactic reboot or power-cycle before (or after) changing/saving settings and save the config only once after all settings you want to change have been changed.
This bug also appears in version 3 firmware, which is just a visual identity update (new TP-Link logo and design) and as such installs even on V2 hardware. Tested on a TL-SG108E V2. A very cheap way to make your switch a V3 switch:
Attachment 4955