Phone no longer connects to Smarty Network

The phone in question was able to use smarty yesterday (30/11/2025) but today it is unable to connect to the smarty network.

I have checked the list of incompatible devices, it isn't there.  (It's a Huawei P20 Lite)

I have reset the phone, rebooted it, still no joy in connecting.  This is my sons phone and he loves it and doesnt understand why he cant ring or text anyone (he is autistic and somethings are harder to explain to him)

Has anyone any advice?