Good afternoon, I'm a beginner in Linux. At my university, I was given the task to install Debian 11 and install a graph on it via the console.Gnome core 40, and then roll 20 packages on top. The last two points seem easy to me, but I've been trying to connect to the proxy of our university for a month.I have probably tried all the methods that I found on the Internet, and I constantly encounter two errors, either 407 proxy authentication required, or "The network is unavailable". We have our own proxy with login, password, proxy host and port.

I tried to configure /etc/environment using and Acquire::http:Proxy and export http_proxy, also created a special file in /etc/apt/apt.conf.d/ proxy.sh and also configured it,
configured /etc/apt/apt.conf file with settings, configured /home/user/.profile

My vice-rector also uses Debian 11 with our proxy, but everything works for him. He shared with me .profile files with export http,export https, export ftp proxy, as well as apt.conf with Acquire::hhtp:roxy. after copying these lines into my files, I also got a 407 error.

Also, when installing the net version of debian 11, when trying to use a proxy to connect to mirrors, I get an error

If anyone has encountered such a problem, tell me what to do

*I have connected to my university proxy from home, but i still cant connect university desktop to proxy