Swedrami: Can confirm that this is NOT the case. I'm still on a rather slow (but therefore consistently stable) connection and downloading one 4 GB .bin chunk through the browser/library takes about 40 minutes. And I hadn't one single instance where the download would just stop and get cancelled after 10 minutes.
Hardly ever had any issues initiating the concurrent download of several of the 4 GB .bin chunks, logging out and leave it downloading over night either. If one or two of the downloads ended up incomplete it was due to getting into the time frame when the ISP does its compulsory reconnection every 24 hours.
Timboli: The link doesn't die while downloading, so no cancel involved. The only issue would be if you lost your connection to GOG and it was after the period of expiry for the link, so no auto resume. This is what some have been experiencing.
As for queued downloads with FDM, have you tried lately?
From the reports I have read it is queued links dying after a time period of about 10 minutes after being added to the queue.
Until a few months ago I was forced to use FDM 5 a lot, but GOG appear to have fixed whatever the server issue was or just paid for more, and so my download speeds with gogcli.exe have been good enough not to need FDM, and so I haven't personally gotten around to checking what has been reported by many now.
Mea culpa, forgot that there's a difference between active and queued downloads for a minute there.
Can't say anything in regards to using any kind of managing solution either, since as described earlier the standard procedure of just downloading several files concurrently through the browser works well enough in my case.
Still doubt that the expiring download links after mere minutes is a thing, though. The "logged in"-token (which is part of every download link) being reset after something like 24 hours of inactivity seems more reasonable, although there were some instances in the recent past, where I had kept the machine running for 3-4 days straight, had not logged out of GoG for those 72-96 hours and had left the library entries (with the download links on display) open for several games in separate browser tabs and still was able to download everything without any indication that the "logged in"-token had been reset at all. I still would have had the compulsory ISP reconnect happening every 24 hours but apparently this wouldn't have affected the "logged in"-token either?