Error: Failed to fetch https://repo.allstarlink.org/public/dists/trixie/InRelease 521 [IP: 2606:4700:3032::ac43:bc5f 443]
Error: The repository ' Index of /public/ trixie InRelease' is no longer signed
Do an apt update again. I was doing some maintenance on the repo server a bit ago and you likely hit a transient moment where the backing store was being moved. Error 521 is the error CloudFlare thows when the backing store isn't reachable.