lapiceroDCS: It is GOG related problem?
Do you have the same problem with other big downloads from elsewhere, using the same browser?
I don't think your issue is very common because otherwise everyone would be up in the arms because we can't download our games. :)
Someone suggested using the old legacy "GOG Downloader", but keep in mind it is already unsupported, and apparently there are already some GOG games that can't be downloaded with it, so don't bet on it.
Also, I personally think it is quite crappy. Unreliable, hard to use (you have to log in to your account BOTH from your web browser, AND that client) etc. If I was using it over a flaky connection, quite often I'd end up with corrupted downloads, no matter what kind of integrity check it is supposed to have. So it is not a foolproof download method either.
I personally would suggest you try the Galaxy client, and download the "backup installers" with it. Or if you are so inclined, let Galaxy download and install the games for you.
Alternatively, if you want to download all your GOG games (the offline installers), you could also try some third-party tools like
gogrepo.py.