Unable to update or upgrade Plesk. The following error is shown:
Error: Failed to download the file http://autoinstall-win.plesk.com/PANEL-WIN_17.8.11/dist-windows/plesk-backend_mu008.msi: Operation too slow. Less than 500 bytes/sec transferred the last 30 seconds
Connection to http://autoinstall-win.plesk.com/ is possible via telnet:
# telnet autoinstall-win.plesk.com 80
Connected to autoinstall-win.plesk.com.
Download from another sources is very slow or not possible as well.
On Windows, it is not possible to download *.msi files manually via browser, for example the file from the error http://autoinstall-win.plesk.com/PANEL-WIN_17.8.11/dist-windows/plesk-backend_mu008.msi
Network connection quality or bandwidth issue.
Contact ISP provider to fix the issue with the network connection quality or bandwidth.
Alternative solution for Windows:
Determine the IP of the nearest CDN using https://dnschecker.org/#A/autoinstall-win.plesk.com and added it to hosts file. Then remove old packages info (inf3 files) from C:ProgramDataPleskInstallercache