do you know the material in the walls of your home? wifi will not go thru brick/concrete/metal
the standard drywall wood stud should be unless you’ve done somn else additional/unique
AC actually performs worse than n or g. you can go farther with g maybe n. but with ac you need to pretty close to your router.
if you have just 1 router, you need to get into the mesh 802.11ac wave 2 type or wifi6 products. multiple runs with physical cable runs. if you that large of a house...
reply to Dennis N as well
re: laptop atennas. it's been a long time since i cracked open laptops, but as i recalled, Dells typically have 1 design and then they add/remove parts to sell variations of the same product on the marketplace. i seemed to recall on certain models you can replace the...
i assume your issue is resolved at this point mike? i quickly scanned the post and it looks like you are basically all set.
a couple of pointers:
-direct wired connection to the modem should get you the max bandwidth of whatever you are supposed to be paying for. cat 5, 5e, 6, 6e, 7, etc...