Hi Majorissues,
welcome to the Apple (user-to-user) Community.
Re: Email messages not downloading to server : Any suggestions?
You have tried some really good trouble-shooting!
Wondering if your iPhone's iOS is up-to-date with the latest iOS version:
About iOS 16 Updates says 16.4.1 is the latest version.
Apple support have a trouble-shooting article online that covers a lot:
What to do: If you can't receive email on your iPhone, iPad, or iPod touch
One example:
Remove your email account and set it up again
- On your computer, sign in to your email provider’s website. Make sure that all of your email is there or make sure that your email is saved somewhere other than your device.
- On your device, go to Settings > Mail, then tap Accounts.
- Tap the email account that you want to remove.
- Tap Delete Account.
- Add your account again.
If these steps don't work, contact your email service provider for more information.
All the best :-)