iMessage inconsistent behaviour, help!!

Hi,

I'm posting mostly to see if there are any peeps that have experienced the issue I am having with iMessage currently. It is related primarily to exchange of messages in a couple of types of scenarios and only began occurring after the iOS 11 upgrade;

Example A: I'm in a good data coverage area, I also know that the receiver is in good data coverage area and before composition iMessage confirms that the the person is iMessage capable in the chat box. I compose and send the message, which sends as a blue iMessage but 9/10 times no 'delivered' is following. After around 5 minutes the message re-sends as an SMS and I presume delivers but can be delivered twice, once as an iMessage and again as SMS. If the exchange continues all messages will be proper functioning iMessages. If there is a gap in time (say ~2hours) and I send another message, then this process starts again exactly as described.

Example B: (Good data coverage also applies) I receive a message, iMessage generally and will respond to the message then roughly 5 minutes after I have got the initial iMessage, I get the same original message as an SMS. This happens with text and picture messages.

Things I have tried.

• Multiple Soft and Hard Reboot of both iDevices (iPhone 6 and SE, iOS 11)
• Multiple iMessage/Facetime off/on cycles on both devices.
• Multiple iCloud sign-out/in cycles on both devices
• Turned of SMS forwarding and iMessage/FaceTime in other locations (Two Macs) so just iPhones connected to the service.

If anyone has experienced anything similar and has had any success in eliminating this behaviour I would love to know how or even if you think you can help pinpoint the device most likely the culprit so I can focus on that one alone would be a great help! I'm presuming it could be iOS update related as the driving factor but honestly thought the steps above would have been the most likely route to get back on track with iMessage. In all the years I've been using this service its never done this.

Thanks for any responses 🙂