Replacing/Adding another cache server

Add the following to /etc/nix/nix.conf:

substituters = https://aseipp-nix-cache.freetls.fastly.net?priority=10 https://cache.nixos.org

cache.nixos.org is the default, with priority 40. See the reference manual. Lower value means higher priority. According to that the substituters are only used when called by a trusted user or in a trusted substituter list.

According to https://nixos.wiki/wiki/Maintainers:Fastly#Beta_.2B_IPv6_.2B_HTTP.2F2 the aesipp-nix-cache is new. It's unclear from when that info is and what the current status of this project is (as of May 2023).