[bombcar]

At some point security updates to iCloud logins break older systems. They don't intentionally break it when an OS goes out of support, but they don't fix it anymore, either.

There are versions of iOS on iPhone that can't do iCloud-stuff anymore.

[alt227]

Generally because the versions of SSL/TLS are outdated on those devices and so either need modern cryptographic libraries installed on them or they just cannot connect to ansy modern server.