Trying to activate iMessage and FaceTime on my MBP (Retina, 13-inch, Early 2015; macOS 10.13.3) keeps returning "An error occurred during activation. Try again."
I have gone through the suggestions on this page, i.e. turning them both off, restarting my phone (model A1586, iPhone 6) and activating them again, but to no avail.
I have also made sure that time zone is automatically set in Date & Time (both on my iPhone and on my mac).
I have reset NVRAM.
I have also ensured that I am actually able to log in to my Apple account online, which works fine.
I have signed out and in iCloud from both phone and MBP.
I have checked that location services is on on my iPhone (have even reset location and privacy settings) and on my computer.
I have checked that my computer's Firewall is Off.
I have reset all my phone settings.
I have rebooted into Safe Mode on the computer.
I get a similar error when I try to make a new user on my mac and log in to Apple Account.
I have created a new Apple ID, which does not work either.
(Where appropriate, I have after each of these steps restarted both phone and computer.)
Does anyone have any other suggestions on what I can try?