No mobile internet after "hard reset"

Hi Paul,
thank for your input.
No, up to now I did not test the SIM (about three years old) in another phone.
How would you explain the effects, that

  • the mobile connection worked fine until the hard reset
  • the boot loop took place after having used the SIM in the phone for about two months without problems
  • calls and SMS are not affected

As far as i’ve read the topic about the boot loop, up to now nobody related the loop to problems with the SIM card.

HB