supamario: I have a feeling that the ISP is limiting access speed to GOG. Here's my reasoning:
My downloads were very slow and often with long pauses of 0 download speed. So I turned on the VPN (I use PIA, but surely it shouldn't matter which you use) to my local city in Australia.. which instantly woke up the speed to full speed - even beyond full speed and even a burst of 2X my max speed!
I wonder if the ISP doesn't like this forced bandwidth and throttles when it sees a connection to GOG.
Basically, try using a VPN and set it to your local server. I am really happy now. This has turned GOG from a frustrating pile of crap, into the best thing.
Good luck.
What forced bandwidth?
You need to explain that better, as it sounds imaginary to me.
With a VPN, if you have one and it isn't a slow free one, you are just using a different route for your downloading.
If your ISP was truly throttling downloads from GOG, they are just as likely to be throttling them from elsewhere too, which is not the case in my experience.
I can use Free Download Manager 5 with multiple streams per file to get my full download speed, all using that slow GOG server. So you'd think my ISP would throttle that too if they had some imaginary issue with GOG.
And depending on where you live in AUS, you either get a good or bad download speed with GOG now. So I don't think it has anything to do with your ISP, and more to do with your location. If you live on the eastern seaboard of AUS and are close to a city, you probably get a good download speed from GOG.
If I thought for a moment that my ISP was to blame, I would be finding out the ISP and location of others also having the same issue and we could complain collectively to that ISP directly.
But lets be clear about throttling. When you are getting a lower speed than usual on a regular basis, you can call that throttling. However, if you are regular getting 204 KB/s downloads or less, that is something else altogether, and not throttling ... more a blockage or extreme limitation.