@Sunshine 

Thank you for taking the time to reply.

And I suspect my initial question was too long and you might not have read that I had tried all of what you have suggested.

I connect to the M7350 absollutely no problem and can use the internet via using it, on my iPhone 12 pro, desktop and laptop. All work fine.

I have mobile data turned off on my phone, in fact I have tried both processes, ie turning Mobile data off and then connecting to it and also connecting to the Mifi and then turning data off. And there is no VPN on the phone but I am grateful for you mentioning to check as I hadn't thought of that previously

neither has solved it.

I have rebooted the device numerous times and again mobile.disktop/laptop etc all connect easily again and get access to the web via the device no problem and they all show as connected but I still get the error in the tpMifi on my iPhone showing as though the device is not connected.

The two images I sent are :-

1) the M7350 screen showing a number 2 i.e. my PC and mobile connected

2) The error I see in the iPhone tpMifi app even when it is connected and data is flowing ok.

The problem I didn't elaborate on previously, is even though you can see the number of  text messages that have arrived are shown on the MiFi screen, the messages are not on the SIM they must be in the device so taking the SIM from the Mifi and moving the SIM to another phone doesn't mean I can read the texts, They simply do not show if the SIM is in another phone, but still show when I put the SIM back in to M7350.

To me it looks like the issue is solely with the part of iPhone app concerned with being able to connect to the device to read it for settings or in this case SMS etc, rather than any problem with internet connection, which works is fine.

Sorry if I was vague previously.

I hope that is clearer