SimpleFTPServer just times out

I'm having trouble with SimpleFTPServer on an ESP32 DevKit V1 (Wrover module based) Using the esp8266_esp32_SPIFFS.ino example in the SimpleFTPServer library directories in Ardino 1.8.19. Libraries have been updated recently. When I FTP to the IP address, the Arduino Serial Monitor says: Connected to LOCUST_2 IP address: 192.168.1.117 SPIFFS opened! FTP: Connected! (( about ten second delay )) FTP: Disconnected! The FTP clients say: 220---Welcome to Simply etc etc 530 Timeout 221 Goodbye I've tried FileZilla, WSFTP and windows and linux command line ftp clients, same results. There is never an input prompt, the FTP client never shows any activity after lo the welcome message. I have applied the #define DEFAULT_STORAGE_TYPE_ESP32 STORAGE_SPIFFS in FtpServerKey.h Is there a fix available? Thanks, Jim