I can't download Quartus lite due to internet connection problem

For further details, you may checkout this.

https://www.avast.com/c-how-to-set-up-a-proxy

As you can see, the proxy server can be something like proxy.example.com with a specific port number. You may try to get the information from your IT department.

Though I can get this info from the Network & internet > Proxy > Use setup script > script address.

I can get a successful connection using my company internet using the manual proxy setting (which already can connect by default).

Regards,

Richard Tan