The sentence ran consecutively to a two-year jail term received in 2016 for attempting to meet a child following sexual grooming.
Hewitt contacted girls on Skype and in online chat rooms, asked them for photographs and encouraged them to touch themselves, the Appeal Court in London heard.
Ms Justice Russell a girl he believed to be of early high school age was an undercover police officer.
An explicit image of a young girl was found on his laptop and he was in breach of a SOPO imposed in 2007.
The judge who jailed Hewitt noted his “very bad record of offences of this type”.
Seven previous convictions spanning 2007 to 2016 included making indecent photos of children and sexual assault.
And, on top of his jail term, the judge imposed an indefinite Sexual Harm Prevention Order (SHPO).
That banned Hewitt from owning, possessing or using devices which can access the internet, except for using computers at public libraries.
New terms were drawn up which will allow Hewitt to access the internet, as long as certain conditions are met.
These include notifying police, making any electronic devices available for inspection and not using software to hide his internet search history.