I suspect that the Sim APN is not compatible if this has happened.
But I can’t be 100 % sure…
The charging issue can be because of a built in protection circuit.
These newer devices are not recommended to be charged all night.
The latest information suggests that charging until full and disconnecting the watch is the better way.
If you have the charging dock you should connect it to a USB power source if charging from empty.
It is designed to be used when the battery reaches around 40% capacity if you are mobile.
If you charge from empty I recommend that you use the cable directly to the watch.
Either way - it is far better to charge until full and then disconnect.
Otherwise it begins the cycle again and I think it is not good for the battery.
It is the same for modern mobile phones.
Overcharging is not a good idea.