The network connection was aborted by the local system

While performing synchronization to FTPS, we are encountering the following error. When we click Retry, the process resumes for some time but the error reoccurs.

The following checks have been completed and verified:

1. Firewall rules for ports 21, 990, and the required data ports are allowed in both directions.
   
2. The WinSCP application is whitelisted in the antivirus.
   
3. Resource utilization on the FTPS server is within normal limits.
   
4. Keepalive and timeout settings are properly configured.
   

Error Log:

It seems that the connection is aborted on the server end.
WinSCP should retry automatically, doesn't it?

I feel this person is more specifically wondering how to deal with the network connection problem.

Its FTPS. There's many possibilities.

Too short timeout. First thing I would do is max out the timeout that WinSCP allows. The default timeout is too short for many reasons. If the device or the network/internet takes too long, this happens.

The server use of the data connection ports may or may not be specified. If not specified you'd have to allow all ports. Often its a wide amount of ports and not having a port open will cause connection problems.

These are the main two that I can think of in a minute. But, there's other things. Anything that can delay or cause time can cause this.