House and original roof are about 20 years old. Roof looks fine. No damage. From a visual stand point it looks good. Have a leak on a porch that has cantilevered construction. So that is part of the roof. What would cause a leak on a roof that looks good and has no visual damage?

Looks good from 2 feet away or from the ground?

20 years is pretty long in the tooth for shingles.

One of the most common causes is a nail that is backed out through the shingle leaving a small hole.

And remember, water runs downhill so the leak may be coming from further up above then where you see the water comes through at.

Roofs are a two part system. The shingles keep everything off the underlayment. The underlayment keeps the house dry.
Then there is the flashing. If the flashing is bad, you can have a leak that starts from a long ways away. Is the leak near a valley or any flashing?
As asked above, looks good from the ground or up on the roof?
What do the gutters look like? Filled with sand/gravel from the roof? That tells you a lot about the shingles.

There is no substitute for a reputable roofing contractor to inspect your roof. And correct the issue.

My small leak was noted in a bedroom ceiling. However, above that spot in the roof as viewed from the attic, there was no water. However, some distance away was a duct passing through the roof, and that duct, bending left and right in the attic, was the water path. Flashing around the duct was wet, and water just droozled along the duct exterior to the attic floor bedroom celing.

Me climbing the roof? Out of the question.

I called the man. Roofer found no sealant under the flashing. How did this flashing without sealant underneath last 20 years without a leak? Slow degradation of shingles, along with seasonal house expansion and contraction which separated a leak path from shingle square to square.

So, you may not see anything visually, as I did not. Even with binoculars (2nd floor). It may be a leak far away from the visual drip.