I encountered the same issue.
I'm not an expert, but I tried some alternatives, and the one that worked was using a VPN connection (download through the browser, not through the software!!!).
I use Kaspersky VPN.
Before initiating downloads, I activate the VPN. Then, I start the download, and the speed increases significantly. Additionally, at times, the download may start slowing down until it reaches 0 kbps. When this happens (and it happened with almost all the downloads I attempted), I simply pause the download, change the VPN server (location) in Kaspersky, and resume the download.
*In some downloads, the VPN server may need to be changed a few times.
*It works really well for me and solves my problem.
*If it doesn't work, maybe I can help by uploading the files to Google Drive and sharing the link, if it is allowed (my email is [email protected]).