Canno write modification time

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Posts: 3
Joined: 8 Oct 2017

ROSt52

PC with Linux Mint 20.1 Cinnamon, updated
Android phone (AP) with docking station and 2 USB Sticks attached
AP and PC are in the same WLAN
FreeFileSynch v 11.11
Android 10
FTP Server: X-plore v 4.27.12
Synching both USB sticks works but Error message:
Cannot write modification time of "ftp://yyy.xxx.x.158/ELECOM USB drive1/System Volume Information/IndexerVolumeGuid~0ad1.ffs_tmp".
CURLE_QUOTE_ERROR: QUOT command failed with 500
500 Unknown command [curl_easy_perform]
and the condition compare by "File Time&Size" does not show that both USB sticks are fully synchronized. Time information is not written.

How can I enable writing of modification time?

Thanks in advance for your help