Almost all big countries now have repository server for Ubuntu. Indonesia for example, the country I live, has its own repository. It is owned by Universitas Indonesia. It named kambing repo. I don’t know why they use kambing (goat in english) but it will be usefull for fast download.
Change all your configuration in /etc/apt/sources.list to http://kambing.vlsm.org
#sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
We need to copy the original just in case something happen and you want to go back to earlier setting
#sudo nano /etc/apt/sources.list
#sudo apt-get update