Hello
I have a client that automatically exchanges small files within the LAN with an FTP server via FTP. With FTP servers from Synology, FileZilla, Tp-Link this works without any problems.
Now I have activated the FTP server on my NetMetal ac² (6.47.4). User rights are activated, folders set up, etc. No firewall rules because within the LAN.
The problem is that the client can send data to the NetMetal, but does not collect any data.
What can be the reason?

Greetings Dirk

If the client has any logs, check those. If not, catch some packets and examine them (you can use Tools->Packet Sniffer on router, filter by client's IP address, save to file and then open it in Wireshark).