Sophos Secure Email iOS error codes AS12 and AS20

We have a user who is getting the error AS12 and AS20 on their iPhone and iPad when using Secure Email.

 

They are also getting the following:

A network error occurred. 

A possible cause is a missing internet connection.

Please check it and try again.

 

User is not on WiFi just 4G.

 

Any help with the codes as a search hasn't revealed anything.

 

Thanks