Home centers sell rolls of 6 in.
Incorrect drip edge gutter installation.
Most premade drip edge flashin.
It is put under the shingles of an attic to flow water directly into the gutter.
Not an uncommon problem.
The guttering should run a few inches lower than your roofline.
Not sure if there s a name for it but i call it drip check.
A gutter apron is installed on the corners above roof decking.
Gutters that are too high can enable runoff water to drip down their back side which in turn can cause deteriorating fascia boards and stains on siding.
Water stains dirt debris and dripping water behind a gutter are usually the result of poorly installed or missing drip edge.
Use tin snips to cut the gutter apron flashing roll in two 3 in.
This works out correctly if you do the eaves first.
One of the reasons is that your shingles may be too short.
A gutter apron is used where shingles are not far enough from the edge of the gutter.
While on the other hand a drip edge is installed to the trim and usually hangs directly behind the back of the gutter.
It should never be installed outside the gutter i e against the fascia board.
If there s a drip edge installed where the fascia meets your shingles and the gutter is hung below the drip edge get some roll flashing and tuck it up under the drip edge and over the top of the gutter.
The whole purpose is to direct the water into the gutters.
There are two reasons for water getting behind the gutter.
On the eave side of a house such as this i install a 3 x3 piece of flashing to slide the gutter under.
With what you have there you d probably be better to install a strip of metal under the drip edge and over the gutter.
The best practice is to always install the drip edge so that it is inside the gutter.