WIFI Strength Drops

I am new here… WIFI Signal will only reach up to 1 bedroom. The 2nd bedroom shows the WIFI SSID but will not allow a connection. It just hangs and drops if not connecting at all. The living room and bedroom are ok. They have Drywall which I know is causing the drop. Mesh Network maybe? Relocate the modem to the center of the apartment. Run a long ethernet cord which I don’t suggest. Thoughts? FYI… the layout of the apartment is like a 'shotgun apartment 'almost

Well you have several options, Add an AP using one of the bands, (2.4 or 5.8) to to do backhaul to the LAN connected AP. Or run a CAT6 cable to a more central location in the apartment. Not sure why you are against this other than you might have issue keeping it out of harms way and tripping hazard. You can run LAN cables 328 feet before you suffer loss due to resistance.

Other option is if your AP has an external antennas, replace them with a higher gain version for both bands. Antenna gain works both ways, added output and higher sensitivity on receive, plus you may want to relocate the AP more centrally, at least some.

Last would be a booster, sort of a Mesh AP that is only powered to extend the WIFI to 2nd bedroom.