Cannot download any packages in Julia 1.11

Looking through some previous cases of such error, it seems that it’s either a problem with the proxy or firewall.

This is the next best post I could find regarding your problem.
If this doesn’t work, I’m afraid your best bet would be using a hotspot without proxy/firewall, or manually cloning https://github.com/JuliaRegistries/General.git to ~/.julia/registries.