And more specifically, are you using Galaxy or directly downloading offline installers? For the past few months I have been getting slower than usual download speeds when downloading offline installers from GOG. Download speeds have averaged around 0.2 MBps/file when downloading large game files. I'm not sure if this because of GOG, but nothing else has changed on my end. Wondering what other people are experiencing now when downloading from GOG.

15-20MB/s using gogrepo script

Are you using Windows 10 by any chance?

In response to your questions, I'm using offline installers and downloading at 30-50 MB/s usually. Sometimes it drops around 10-20, rarely below 10.

Yes, I am using Windows 10. I have heard about issues with Windows 10 degrading internet speeds, but I have not found any indication that this is my problem. I don't have issues with any other websites. What OS are you using?

open task manager, goto services and stop update orchestrator and windows update and see if things work as expected.

Haven't paid attention on offline installers, but for now...

Galaxy .8 MB/s

Windows 10 Pro. I was asking because I faced such issues a few months ago. Apparently the download speed got capped somewhere around 1.2 MB/s - tested on several websites (GOG, moddb, nexus, etc). I found that very strange since it was working properly on Linux Mint.
Yours sounds like a different problem though. For future reference you might want to have a look at this:
https://superuser.com/questions/1330112/windows-10-internet-speed-capped-at-half-the-original-speed-on-new-pc#1330155

gogrepo.py usually maxes out my connection., Galaxy is a bit slower.

Thank you. The first reference in your link seemed to help.

Direct download, 250/100 fiber, getting 28.6 MB/s on Drox Operative 2 (1.1GB)