Indoor mosquitos eating my 4yo alive

I have a weird mosquito issue in only one of the rooms in my house. If you go in there day or night, you can't see or find any mosquitoes. But every morning my 4-year-old wakes up with a dozen bites.

Is it possible they're coming through the a/c vent? There's no standing water, and the window is sealed. The only other thing I can think of is that they could be coming in through the soffits, as the room is on the second floor and above our open porch. It's otherwise next to and below the attic.

I tried using an indoor/outdoor zapper in the room. It possibly worked but is not a long-term solution.

Should I get a better zapper? Should I make or buy some kind of trap?

Every night we have to lather up the kid in natural bug spray and repellant lotions and hope it works. I suppose a mosquito net is next.