I have the same problem as this guy from the forum:
Every few minutes the connection drops with the error
Download Error: Connection closed by lower level protocol
I am using Version 5.4.0 build 3970.
I usually have multiple FlashFXP sessions open that download stuff.
Every few minutes one of those FlashFXP windows drops speed down to 0,0 KB/s and after some seconds gets a "Connection closed" error.
The other sessions are continuing download like nothing happened but usually experience the same problems some minutes later. The internet connection itself is stable and present all the time, no ping drops while those closed connections happen. The closed connection gets immediately reconnected and starts downloading again. But it still is very annoying.
SSHD from the server I'm downloading has
enabled, but I changed those and restarted the server, still happens. I can't find anything useful in the debug logs from the server. Plus, the 300 seconds keep alive interval rarely gets reached at all, as you can see in the pastebin.
I put an example log on pastebin: https://pastebin.com/B4TSWvvZ
Microsoft Windows 10 Pro
Version 10.0.16299 Build 16299
If you need any more info, let me know