Maybe this will help:
Go to Settings - General - Language & Region - iPhone Language and set a different language for the iPhone. When the new language is set up, and your device is using it, set the language back to your language (same procedure as before).
I think that the fact that this problem manifests on both an iPhone and a laptop indicate that the problem is likely external to both devices. If it's been less than 90 days since you purchased the iPhone 6, you may want to take advantage of the free telephone technical support by calling and talking to a technical support specialist.