If you are getting an error in your BOINC client log:

Scheduler request failed: Peer certificate cannot be authenticated with give


you must update/replace the ca-bundle.crt from the BOINC client. It looks like the file is outdated. Stop BOINC, replace the file and restart.

I put the file in the download folder for download.

https://srbase.my-firewall.org/sr5/d.../ca-bundle.crt

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