iMessage wont work on my iPhone 11 Pro

I have an iPhone 11 Pro and use my apple ID. I'd been using iMessage for quite a while when suddenly my messages stopped delivering. It just came up with that little exclamation mark in the red circle. I googled for help and majority of the sites said to sign out, restart your device, then sign back in. So this is what I did. I also reset my settings, changed my apple ID password and updated my phone.

Now, every time I try to sign back in on both devices, it says 'An error occurred during authentication.'

Now I can't even sign back into my iMessage. What do I do?