There is no data cap. I have recently downloaded almost 1TB in a single day at a fairly constant 200mb/s.

But you're not imagining things. In the past few weeks, quite a few people complained about similar issues and they all had one thing in common. They were all from Australia.

There is obviously some issue about downloading GOG stuff from Australia. I suggest you Australians get somehow together and approach GOG about it as a group.

I don't think there's a cap, since I downloaded 2.5TB of my library yesterday.
(Need to stay up to date on current versions of the games right now, just in case.)

Well, fuck me sideways. I was just about to brag how I've downloaded 250GB in one swoop from gog.com like a month ago... but then I see these these "oh I just downloaded 2.5 terabytes yesterday, and today I am going to download it all all over again because why not?".

Ok I feel humble now. ANYWAY, I still think it would be a great idea if GOG set up a system people can download the installers using peer-to-peer protocols, even their own Bittorrent clients, like how Humble Bundle allows. I am confident it would increase everyone's, even poor Aussies', download speeds to incredible rates. Unfortunately I am not seeing GOG using resources to implement that stuff, unless they finally realize it could help them too.

I have a 400Mbit/s line at home but with GOG I don't get even half of that, usually at max something like 40-50Mbit/s... but I think it is something at my end as at work I do seem to be able to download GOG installers at much higher speeds. There may be other bottlenecks in my system like how I tend to download the installers directly to my USB HDD which is running ntfs-3g in Linux which seems to slow file operations too etc. etc. etc.

Ah yea that'll be it. I didnt think to see that angle, thanks for the enlightenment. It'll be some kind of transit cap between wherever gog hosts the files and international (well AU at least) enforcing the limit. The solution would be for gog to have a local server hosting their catalogue, my guess is, obviously, they dont have one.

I think GOG does use several (third-party) CDN servers for the downloads (and other content, like the web pages), all over the world.

Maybe the servers where Australians usually get connected is somehow overstressed, or in an inconvenient place for Australians, like somewhere in SE Asia.

https://www.comparebroadband.com.au/broadband-articles/latest-news-id3/where-does-australia-get-its-fixed-line-broadband-internet-from-id738/

They do, as far as I know. My guess is that's where the problem is.

The only DL speed problems i've ever had is when some big game is released. Servers get loaded but even in that case it's always not lower than 50Mbit/s. Even when CP2077 was released and a LOT of people were downloading the game my DL speed was about 5Mb/s at worst. It even went up to 177Mb/s for a few minutes which means that GOG servers can serve more than 1Gbit/s.

So yeah it looks like the problem is elsewhere.