Just tried to download a offline installer. Can't complain, I got 16MiBs+ constantly, which is a bit slower than the normal speed, but still good. Of course it's not representative for the whole world.

With everything that's going on, some internet nodes might be damaged or sabotaged.

So it's not solely what passes for "high speed internet" here in Ausfailure, that is causing such slow downloads from GOG.
File 7 of FO4 (.bin 6) as at 2023-8-21 11:15pm AEST
36.4 KB/s - 1.0 GB of 4.0 GB, 1 day left

There was a good discussion in another thread, and apparently a way (by Timboli) to find out where GOG would be directing you to download your offline installers (albeit you may get different results with different tries):

https://www.gog.com/forum/general/what_is_happening_with_download_speeds_on_the_offline_backup_files_its_a_snails_pace_now/post12

So for example I am getting great download speeds as I am downloading from a server which is apparently in the same country (same city even, 12 km from me), while e.g. Australians seem to be downloading from abroad, US west coast servers, for some reason.

Fastly.com seems to have two download servers in Johannesburg and Cape Town, not sure if you should be able to download your GOG installers from either of them...

Thanks for the information, it is very interesting, I'll check it out.

After looking it up, I am connecting to a server in London. Maybe other people are having issues with this server. If I remember correctly, we usually connect to central European servers from here in South Africa, so it is a bit unusual that it is a server in London, or maybe I don't know what I am talking about haha.

I can't even connect to the initial Fastly link that Timboli posted, so I've no way to find out what cdn server I'm being made to download from.

What are you downloading with? Galaxy or Browser, etc.

If browser, you should be able to see the download link (in properties), and the first portion of that is what you need to check with, minus the https:// portion.
i.e. gog-cdn-fastly.gog.com

Then in a command prompt you need to run - nslookup gog-cdn-fastly.gog.com

In part of the result for that, you will see the web address you need to use with https://www.ipaddress.com/ip-lookup

The result from that will show you where you are connected.

I recommend using Free Download Manager 5 to do your GOG downloads while this slow issue persists. For that to work, you need to install that program, plus an addon for it in your browser. I use Brave, a chrome clone, and I have it setup so that I need to hold down my ALT key while clicking a browser download link. FDM5 will then capture the correct download link. You can queue up other links, and there no longer seems to be a time limitation like there was.

With FDM5 I am back to my usual download speed or slightly better at times, no doubt due to multi-threading.

Browser.
I refuse to use GOG Galaxy 2.x, as it's alpha grade code which was forced on users as a 'public beta'.
In the other thread, with the link being posted in full, with the https and being clickable, I'd thought you needed to go directly to the link in browser, first. Which gets me gog-cdn.us-eu.map.fastly.net
So the US servers, which, considering the usual speed US to AU, should be faster And that last bit gets me where, exactly the servers are. I use Brave, as well.
Haven't looked at using download managers in a long while. Seems I might need to look at them again.

I suggest you use the IP address, not the hostname.

So for example in my case:

nslookup gog-cdn-fastly.gog.com

gives:

Non-authoritative answer:
Name: gog-cdn.us-eu.map.fastly.net
Address: 151.101.245.55
Aliases: gog-cdn-fastly.gog.com

Then in https://www.ipaddress.com/ I search for 151.101.245.55 which in my case gives a location in Helsinki, Finland.

If I search for gog-cdn.us-eu.map.fastly.net instead, it gives the location to St Louis Missouri US.

My good friend TheDcoder, a young man from India, and a member here, knows a lot more about networking and related than I do.

He just sent the following message to me.

I doubt GOG has anything much to do with it, CDNs are responsible for routing, not the content provider
GOG just gives them the files to distribute, the rest is up to the CDNs.

If that is true, then I have been laying some of the blame at the wrong door. Seems weird though, that a service like that would have someone at the bottom of AUS, downloading from North America.