SLOW download via normal FTP.

After several years of using WinSCP, it stopped downloading faster than 100 to 200 kB/s as of Jan 12, 2021. I use it exclusively on DriveHQ (DHQ). The DHQ file manager downloads at 2 to 3 MB/s. I upgraded to beta 5.18.1 and still have pathetic download speed; sometimes it disconnects. My internet speed test is always over 50 MB/s, regardless of where the server is that I connect to.

Haven't you enabled debug logging?
https://winscp.net/eng/docs/faq_slow#logging

Actually, no, debug logging is not enabled and never has been. All logging is disabled. So, there has been no change in any preferences conditions. Very kind of you to suggest checking.

Does DHQ file manager use FTP? Or is it something proprietary? Can you download the files faster using any actual FTP client?