Contacts and Messages are not synching across all my devices linked in my iCloud. Help.

Hello herbertliverdoc,

Let's verify that all devices are signed into iCloud:

"Sign in to iCloud on all your devices

To set up iCloud on your devices, sign in to each of them with the same Apple ID and password. You can choose which apps store information in iCloud and which iCloud features you’re using separately on each device. Learn more about how each app or feature uses iCloud.

Note: When you turn off iCloud for an app or feature on a device, information stored in iCloud for that app or feature is no longer available on that device. However, it’s still available on other devices where iCloud is turned on for the app or feature. See How iCloud keeps information up to date across all your devices.

Set up iCloud on your iPhone, iPad, or iPod touch

1. On your iPhone, iPad, or iPod touch, go to Settings > [your name].
2. If you don’t see [your name], tap “Sign in to your [device],” then enter your Apple ID and password.
3. Do one of the following:

• iOS 16, iPadOS 16, or later: Tap iCloud, then turn on each app or feature you want to use. Tap Show All to see more apps.
  • 
  • iOS 15, iPadOS 15, or earlier: Tap iCloud, then turn on each app or feature you want to use.

Set up iCloud on your Mac

1. On your Mac, do one of the following:

• macOS Ventura: Choose Apple menu  > System Settings, click [your name] at the top of the sidebar, then click iCloud on the right.
  • If you don’t see your name, click Sign in with your Apple ID, enter your Apple ID and password, then click iCloud.
• macOS 12 or earlier: Choose Apple menu  > System Preferences, click Apple ID, then click iCloud.
  • If you don’t see Apple ID, click Sign In, enter your Apple ID and password, then click iCloud.

1. Turn on or select each app or feature.
2. 

Set up iCloud on your Apple Watch

• For an Apple Watch you pair with your iPhone: If you turn on iCloud for an app or feature on your iPhone, you can see information from that app or feature on your Apple Watch (if available). You can choose what information appears on your Apple Watch by changing settings in the Apple Watch app on your iPhone. See The Apple Watch app in the Apple Watch User Guide.
• For an Apple Watch set up by a family member: You can use the Settings app on the Apple Watch to turn iCloud on or off for an app or feature.

"

Sign in to iCloud on all your devices - Apple Support

Cheers.