After change
vim /etc/apt/sources.list.d/unipi.list as you wrote, everything works
#deb https://files.unipi.technology/debian stretch main
deb https://repo.unipi.technology/debian stretch main
thanks for support
After change
vim /etc/apt/sources.list.d/unipi.list as you wrote, everything works
#deb https://files.unipi.technology/debian stretch main
deb https://repo.unipi.technology/debian stretch main
thanks for support