It's not so much about smiling or not smiling, but more subtle facial movements, mainly your eyes.
You have a very common problem, your eyes look "dead". Like you've been on your computer for 12 hours and are tired. And your brow is too tense, like you are worried or sad.
All of these things hurt your subcomms. It basically communicates boredom, laziness, lack of focus, lack of energy.
Just smiling won't fix this, because it feels fake and other people also easily pick up on it.
You need to smile with your whole face, or only with your eyes.
You need to have more awareness of what kind of vibe you are projecting to other people with your body language, but specially with your face.
It's hard to do it on purpose though. The right vibe generally comes as a result of an spontaneous spike of emotion. It requires practice and a general awareness of the inner emotional states that trigger a good vibe.
Some things that might be helpful:
-Relax your brow and let it drop.
-In general, relax your face.
-Have some anchor that makes you smile naturally (a joke, a good memory). Try to "smile with your whole face"
-Try to focus your eyes into a distant object in the background. The idea is to look more engaged or focused.
I attached 2 photos as an example. I strongly believe this isn't nitpicking. All of those subtleties add up and can add or substract to your baseline attractiveness.