I don't use Galaxy, but the fact that it's also failing on the GOG website must mean that it's a problem on GOG's servers. Did you send in a Support ticket?

No because even though it said that it failed the whole file still made it to my hard drive and both the files from the site and Galaxy were the same size 1,575,904 KB and both seem to run (I didn't actually install but they both made it to the setup menu). I have no idea what's going on but if you're still having a problem definitely send a ticket.

Is anyone else still having issues downloading the latest version of Train Fever? For multiple days, everytime I try to download Train Fever it keeps saying the download failed. The other GOG games download fine. Why is it just this one game that's having issues? Isn't this a GOG server problem?

Just download the patch from browser (Firefox) and Galaxy, no problem at all.
Perhaps switching to another browser and download it?

At what point is it failing? When I tested it, it seemed strange because it failed after it finished the entire download (like it was timing out rather than failing). So when I looked it was actually there. It's a strange error, but if it's getting to the end like mine did then it could be an AV thing, or maybe it's just stuck in your temp files or as a .part file somewhere. If it's the size I mentioned above then you should have the whole thing even if it's saying that it's not actually completing the dl. Maybe you could try doing a search on your computer for setup_train_fever

I still think it's a server issue since this is the only GOG game that has this strange download problem.

Meanwhile there since 25.02. Build 7753. unfortunately not yet at GOG.

gog.com/forum/train_fever/build_7753

Translated with Google.