Problem finally solved

I probably looked at it 50 times on each device (phone, tablet etc) and never realised that the telephone number was no longer ticked. Probably due to the eSim I had installed when traveling to Africa.

A few weeks ago I suddenly could not send SMS or iMessages from my iPad, MacBook Air or iMac anymore. However, all messages received on my iPhone are still shown in the above mentioned items.

I have tried all recommended settings to no avail.

Am I the only one in this situation? Can anyone help me?

Below are the recommended settings which I have checked:

If your Mac Book Air can receive iMessages and SMS but cannot send, here are some steps to troubleshoot the issue:

1. Check Internet Connection: Ensure that your Mac is connected to the internet. You should be able to load webpages and receive emails.
2. Restart Your Mac: Sometimes a simple restart can resolve messaging issues.
3. Update macOS: Install the latest macOS updates to ensure your system is up-to-date.
4. Verify Date & Time Settings: Make sure the date and time on your Mac are correct. Incorrect settings can affect messaging.
5. Check Recipient Details: Confirm that you’re addressing messages to the correct phone number or email address.
6. Text Message Forwarding: If you’re using iMessage, ensure that your iPhone is turned on and that Text Message Forwarding is set up correctly. This allows messages to sync between your iPhone and Mac.