Undoubtedly, Comcast is handing you a DNS server different from your mobile. On the desktop, archive.* just failed when I am using iCloud Private Relay. Mobil

Undoubtedly, Comcast is handing you a DNS server different from your mobile. On the desktop, archive.* just failed when I am using iCloud Private Relay. Mobile works with the same setting. (wi-fi and wireless only) With ICPR, you can choose country+timezone or general location. Just another thing to check. May not apply to you.