I don't think any of this solutions posted here fixes the problem, in my mind it was just "luck".
I tried everything already mentioned here (I won't wipe all my devices, one is enough).
I own 5 iDevices:
- iPhone 6s on iOS 9.0.2
- iPhone 5s on iOS 9.0.2
- iPhone 5 on iOS 9.2.1
- iPad mini retina on iOS 9.0.2
- iPhone 4 on iOS 7.1.2
Only on the iPhone 4 the iCloud backup works.
I've made the iPhone 5 completely new from scratch.
I've tried a backup while connected to the same wireless network with the same DNS servers.
While the backup was successful with the iPhone 4, the backup on the other devices (I tried all on iOS9) failed.
Here is the syslog while the device tries to perform a backup.
I've replaced 2 strings which looked like an ID to me, also I've replaced the devicename. Just to get sure.
To outline it: The device was NOT offline as the log says. There are no restrictions which could prevent communication. Synchronization of the other iCloud stuff (bookmarks, pictures, keyboard shortcuts, ...) works without any troubles.
Jan 25 13:42:06 iPhone6s backupd[974]: INFO: Starting backup
Jan 25 13:42:06 iPhone6s backupd[974]: INFO: All subsystems go, let's run this backup
Jan 25 13:42:06 iPhone6s backupd[974]: INFO: ========== Backup starting
Jan 25 13:42:06 iPhone6s backupd[974]: INFO: DeviceID="<REMOVED-1>", DeviceName="iPhone6s", ProductType="iPhone8,1", BuildVersion="13A452"
Jan 25 13:42:07 iPhone6s kernel[0]: AppleKeyStore: operation failed (pid: 974 sel: 23 ret: e00002f0 '-536870160')
Jan 25 13:42:07 iPhone6s backupd[974]: INFO: Setting up backups for this device (<REMOVED-2>)
Jan 25 13:42:07 iPhone6s backupd[974]: INFO: Resetting cache database
Jan 25 13:42:07 iPhone6s backupd[974]: INFO: Setting up backup keybag for device <REMOVED-2>
Jan 25 13:42:07 iPhone6s kernel[0]: AppleKeyStore: operation failed (pid: 974 sel: 23 ret: e00002f0 '-536870160')
Jan 25 13:42:07 iPhone6s backupd[974]: INFO: Creating keybag
Jan 25 13:42:07 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 57 failed: 5 - Expensive path prohibited
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Save operation 2A48B879-1157-40B1-AD17-9CBB24452499 completed with error: <CKError 0x156d76d60: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)>: <CKError 0x156d76d60: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156d76d60: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: All items in failed operation 2A48B879-1157-40B1-AD17-9CBB24452499 retried, not recording error
Jan 25 13:42:07 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 58 failed: 5 - Expensive path prohibited
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Save operation BF38A639-D1E3-48D5-B028-69F1F1123F00 completed with error: <CKError 0x156dafc10: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)>: <CKError 0x156dafc10: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156dafc10: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: All items in failed operation BF38A639-D1E3-48D5-B028-69F1F1123F00 retried, not recording error
Jan 25 13:42:07 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 59 failed: 5 - Expensive path prohibited
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Save operation 7200BB08-E70F-4013-8210-9AD6251A9AA6 completed with error: <CKError 0x156e571b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)>: <CKError 0x156e571b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156e571b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: All items in failed operation 7200BB08-E70F-4013-8210-9AD6251A9AA6 retried, not recording error
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Record <CKRecordID: 0x156d71190; K:g+v23wZJT0+M2fyyJU80gg==:(mbksync:__defaultOwner__)> has failed to save 3 times. Giving up with error <CKError 0x156e571b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: ERROR: Failed to save MBCKKeyBag: <CKError 0x156e571b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:07 iPhone6s backupd[974]: ERROR: Error saving keybag to server
Jan 25 13:42:07 iPhone6s backupd[974]: INFO: Retrying after soft error: The Internet connection appears to be offline. (CKErrorDomain/3). Underlying error: The Internet connection appears to be offline. (NSURLErrorDomain/-1009).
Jan 25 13:42:07 iPhone6s backupd[974]: WARNING: Retrying after error: <CKError 0x156e571b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s kernel[0]: AppleKeyStore: operation failed (pid: 974 sel: 23 ret: e00002f0 '-536870160')
Jan 25 13:42:08 iPhone6s backupd[974]: INFO: Setting up backups for this device (<REMOVED-2>)
Jan 25 13:42:08 iPhone6s kernel[0]: AppleKeyStore: operation failed (pid: 974 sel: 23 ret: e00002f0 '-536870160')
Jan 25 13:42:08 iPhone6s backupd[974]: INFO: Setting up backup keybag for device <REMOVED-2>
Jan 25 13:42:08 iPhone6s backupd[974]: INFO: Creating keybag
Jan 25 13:42:08 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 60 failed: 5 - Expensive path prohibited
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Save operation 8D4EA9A1-55E0-441F-BD33-0703E3A66436 completed with error: <CKError 0x156d7b330: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)>: <CKError 0x156d7b330: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156d7b330: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: All items in failed operation 8D4EA9A1-55E0-441F-BD33-0703E3A66436 retried, not recording error
Jan 25 13:42:08 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 61 failed: 5 - Expensive path prohibited
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Save operation 15792D4E-A611-4006-A255-C1FF8BD202E1 completed with error: <CKError 0x156e5d7b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)>: <CKError 0x156e5d7b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156e5d7b0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: All items in failed operation 15792D4E-A611-4006-A255-C1FF8BD202E1 retried, not recording error
Jan 25 13:42:08 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 62 failed: 5 - Expensive path prohibited
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Save operation F32B899F-71FC-4808-8F25-EF9FF2C92973 completed with error: <CKError 0x156da9800: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)>: <CKError 0x156da9800: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156da9800: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: All items in failed operation F32B899F-71FC-4808-8F25-EF9FF2C92973 retried, not recording error
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Record <CKRecordID: 0x156d73040; K:q+2NOSTrQwuhlheyVUY98A==:(mbksync:__defaultOwner__)> has failed to save 3 times. Giving up with error <CKError 0x156da9800: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: ERROR: Failed to save MBCKKeyBag: <CKError 0x156da9800: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:08 iPhone6s backupd[974]: ERROR: Error saving keybag to server
Jan 25 13:42:08 iPhone6s backupd[974]: INFO: Retrying after soft error: The Internet connection appears to be offline. (CKErrorDomain/3). Underlying error: The Internet connection appears to be offline. (NSURLErrorDomain/-1009).
Jan 25 13:42:08 iPhone6s backupd[974]: WARNING: Retrying after error: <CKError 0x156da9800: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:09 iPhone6s kernel[0]: AppleKeyStore: operation failed (pid: 974 sel: 23 ret: e00002f0 '-536870160')
Jan 25 13:42:09 iPhone6s backupd[974]: INFO: Setting up backups for this device (<REMOVED-2>)
Jan 25 13:42:09 iPhone6s backupd[974]: INFO: Resetting cache database
Jan 25 13:42:09 iPhone6s backupd[974]: INFO: Setting up backup keybag for device <REMOVED-2>
Jan 25 13:42:09 iPhone6s kernel[0]: AppleKeyStore: operation failed (pid: 974 sel: 23 ret: e00002f0 '-536870160')
Jan 25 13:42:09 iPhone6s backupd[974]: INFO: Creating keybag
Jan 25 13:42:10 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 63 failed: 5 - Expensive path prohibited
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Save operation B1B121C2-9AA5-421C-AA2D-7B3C6792F853 completed with error: <CKError 0x156db3e70: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)>: <CKError 0x156db3e70: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156db3e70: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: All items in failed operation B1B121C2-9AA5-421C-AA2D-7B3C6792F853 retried, not recording error
Jan 25 13:42:10 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 64 failed: 5 - Expensive path prohibited
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Save operation 8171255A-83B0-482A-A9F9-C2844C394C43 completed with error: <CKError 0x156e55fb0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)>: <CKError 0x156e55fb0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156e55fb0: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: All items in failed operation 8171255A-83B0-482A-A9F9-C2844C394C43 retried, not recording error
Jan 25 13:42:10 iPhone6s cloudd[606]: tcp_connection_handle_connect_conditions_bad 65 failed: 5 - Expensive path prohibited
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Save operation 5C3998C7-D948-4DA0-ADB7-3684D320E3F0 completed with error: <CKError 0x156db3f40: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Handling save error for record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)>: <CKError 0x156db3f40: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Save of record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> hit a network failure: <CKError 0x156db3f40: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Retrying save of record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> after 0.00 seconds
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: All items in failed operation 5C3998C7-D948-4DA0-ADB7-3684D320E3F0 retried, not recording error
Jan 25 13:42:10 iPhone6s backupd[974]: WARNING: Record <CKRecordID: 0x156d74040; K:ExrmcRoMQO2mJzH/sFWjXA==:(mbksync:__defaultOwner__)> has failed to save 3 times. Giving up with error <CKError 0x156db3f40: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: ERROR: Failed to save MBCKKeyBag: <CKError 0x156db3f40: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: ERROR: Error saving keybag to server
Jan 25 13:42:10 iPhone6s backupd[974]: INFO: Not retrying after soft error: The Internet connection appears to be offline. (CKErrorDomain/3). Underlying error: The Internet connection appears to be offline. (NSURLErrorDomain/-1009).
Jan 25 13:42:10 iPhone6s backupd[974]: ERROR: Backup failed: <CKError 0x156db3f40: "Network Unavailable" (3/-1009); "The Internet connection appears to be offline.">
Jan 25 13:42:10 iPhone6s backupd[974]: ERROR: ========== Backup failed: The Internet connection appears to be offline. (CKErrorDomain/3). Underlying error: The Internet connection appears to be offline. (NSURLErrorDomain/-1009).
Jan 25 13:42:10 iPhone6s Preferences[774]: Failed backup: Error Domain=MBErrorDomain Code=308 "The Internet connection appears to be offline." UserInfo={NSLocalizedDescription=The Internet connection appears to be offline.}